diff --git a/src/DiDom/Document.php b/src/DiDom/Document.php
index 4d202bc..53be63b 100644
--- a/src/DiDom/Document.php
+++ b/src/DiDom/Document.php
@@ -15,29 +15,35 @@ class Document
      */
     protected $document;
 
+    /**
+     * @var string
+     */
+    protected $type;
+
     /**
      * Constructor.
      * 
-     * @param  string $html HTML code or file path
+     * @param  string $string HTML or XML string or file path
      * @param  bool   $isFile indicates that in first parameter was passed to the file path
      * @param  string $encoding The document encoding
+     * @param  string $type The document type
      */
-    public function __construct($html = null, $isFile = false, $encoding = 'UTF-8')
+    public function __construct($string = null, $isFile = false, $encoding = 'UTF-8', $type = 'html')
     {
-        if ($html instanceof DOMDocument) {
-            $this->document = $html;
+        if ($string instanceof DOMDocument) {
+            $this->document = $string;
 
             return;
         }
 
+        if (!is_string($encoding)) {
+            throw new InvalidArgumentException(sprintf('%s expects parameter 3 to be string, %s given', __METHOD__, gettype($encoding)));
+        }
+
         $this->document = new DOMDocument('1.0', $encoding);
 
-        if ($html !== null) {
-            if ($isFile) {
-                $this->loadHtmlFile($html);
-            } else {
-                $this->loadHtml($html);
-            }
+        if ($string !== null) {
+            $this->load($string, $isFile, $type);
         }
     }
 
@@ -85,34 +91,58 @@ public function appendChild($node)
     }
 
     /**
-     * Load HTML from a string.
+     * Load HTML or XML.
      * 
-     * @param  string $html The HTML string
-     *
-     * @return \DiDom\Document
-     *
-     * @throws \InvalidArgumentException if the provided argument is not a string
+     * @param  string $string HTML or XML string or file path
+     * @param  bool   $isFile indicates that in first parameter was passed to the file path
+     * @param  string $type Type of document
      */
-    public function loadHtml($html)
+    public function load($string, $isFile = false, $type = 'html')
     {
-        if (!is_string($html)) {
-            throw new InvalidArgumentException(sprintf('%s expects parameter 1 to be string, %s given', __METHOD__, (is_object($html) ? get_class($html) : gettype($html))));
+        if (!is_string($string)) {
+            throw new InvalidArgumentException(sprintf('%s expects parameter 1 to be string, %s given', __METHOD__, (is_object($string) ? get_class($string) : gettype($string))));
+        }
+
+        if ($isFile) {
+            $string = $this->loadFile($string);
+        }
+
+        if (!is_string($string) or !in_array(strtolower($type), ['xml', 'html'])) {
+            throw new InvalidArgumentException(sprintf('Document type must be "xml" or "html", %s given', __METHOD__, (is_object($type) ? get_class($type) : gettype($type))));
+        }
+
+        if (substr($string, 0, 5) !== '<?xml') {
+            $prolog = sprintf('<?xml encoding="%s">', $this->document->encoding);
+            $string = $prolog.$string;
         }
 
-        $prolog = sprintf('<?xml encoding="%s">', $this->document->encoding);
-        $html = $prolog.$html;
+        $this->type = strtolower($type);
 
         libxml_use_internal_errors(true);
         libxml_disable_entity_loader(true);
 
-        $this->document->loadHtml($html);
+        $this->type === 'xml' ? $this->document->loadXml($string) : $this->document->loadHtml($string);
 
         libxml_clear_errors();
 
         libxml_disable_entity_loader(false);
-        libxml_use_internal_errors(false);
+        libxml_use_internal_errors(false);   
 
-        return $this;
+        return $this;   
+    }
+
+    /**
+     * Load HTML from a string.
+     * 
+     * @param  string $html The HTML string
+     *
+     * @return \DiDom\Document
+     *
+     * @throws \InvalidArgumentException if the provided argument is not a string
+     */
+    public function loadHtml($html)
+    {
+        return $this->load($html, false, 'html');
     }
 
     /**
@@ -127,6 +157,41 @@ public function loadHtml($html)
      * @throws \RuntimeException if you are unable to load the file
      */
     public function loadHtmlFile($filepath)
+    {
+        return $this->load($filepath, true, 'html');
+    }
+
+    /**
+     * Load XML from a string.
+     * 
+     * @param  string $xml The XML string
+     *
+     * @return \DiDom\Document
+     *
+     * @throws \InvalidArgumentException if the provided argument is not a string
+     */
+    public function loadXml($xml)
+    {
+        return $this->load($xml, false, 'xml');
+    }
+
+    /**
+     * Load XML from a file.
+     * 
+     * @param  string $filepath The path to the XML file
+     *
+     * @return \DiDom\Document
+     *
+     * @throws \InvalidArgumentException if the file path is not a string
+     * @throws \RuntimeException if the file does not exist
+     * @throws \RuntimeException if you are unable to load the file
+     */
+    public function loadXmlFile($filepath)
+    {
+        return $this->load($filepath, true, 'xml');
+    }
+
+    protected function loadFile($filepath)
     {
         if (!is_string($filepath)) {
             throw new InvalidArgumentException(sprintf('%s expects parameter 1 to be string, %s given', __METHOD__, gettype($filepath)));
@@ -138,15 +203,13 @@ public function loadHtmlFile($filepath)
             }
         }
 
-        $html = file_get_contents($filepath);
+        $content = file_get_contents($filepath);
 
-        if ($html === false) {
+        if ($content === false) {
             throw new RuntimeException(sprintf('Could not load file %s', $filepath));
         }
 
-        $this->loadHtml($html);
-
-        return $this;
+        return $content;
     }
 
     /**
@@ -215,6 +278,16 @@ public function html()
         return trim($this->document->saveXML($this->getElement()));
     }
 
+    /**
+     * Dumps the internal document into a string using XML formatting.
+     * 
+     * @return string The document html
+     */
+    public function xml()
+    {
+        return trim($this->document->saveXML());
+    }
+
     /**
      * Nicely formats output with indentation and extra space.
      * 
@@ -263,6 +336,16 @@ public function is($document)
         return $this->getElement()->isSameNode($element);
     }
 
+    /**
+     * Returns the type of document (XML or HTML).
+     * 
+     * @return string
+     */
+    public function getType()
+    {
+        return $this->type;
+    }
+
     /**
      * @return \DOMDocument
      */
@@ -294,7 +377,7 @@ public function toElement()
      */
     public function __toString()
     {
-        return $this->html();
+        return $this->type === 'xml' ? $this->xml() : $this->html();
     }
 
     /**
diff --git a/src/DiDom/Element.php b/src/DiDom/Element.php
index cc60c74..54cf570 100644
--- a/src/DiDom/Element.php
+++ b/src/DiDom/Element.php
@@ -164,6 +164,16 @@ public function html()
         return $this->toDocument()->html();
     }
 
+    /**
+     * Dumps the internal document into a string using XML formatting.
+     * 
+     * @return string The node xml
+     */
+    public function xml()
+    {
+        return $this->toDocument()->xml();
+    }
+
     /**
      * Get the text content of this node and its descendants.
      * 
diff --git a/tests/DiDom/DocumentTest.php b/tests/DiDom/DocumentTest.php
index ff9e165..8936c91 100644
--- a/tests/DiDom/DocumentTest.php
+++ b/tests/DiDom/DocumentTest.php
@@ -16,6 +16,14 @@ public function testConstructWithInvalidArgument()
         $document = new Document(array('foo'));
     }
 
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testConstructWithInvalidEncoding()
+    {
+        $document = new Document(array('foo'));
+    }
+
     /**
      * @expectedException RuntimeException
      */
@@ -24,6 +32,58 @@ public function testConstructWithNotExistingFile()
         $document = new Document('path/to/file', true);
     }
 
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testConstructorWithInvalidArgumentType()
+    {
+        $document = new Document('foo', false, 'UTF-8', null);
+    }
+
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testConstructorWithInvalidDocumentType()
+    {
+        $document = new Document('foo', false, 'UTF-8', 'bar');
+    }
+
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testLoadWithInvalidContentArgument()
+    {
+        $document = new Document();
+        $document->load(null);
+    }
+
+    /**
+     * @expectedException RuntimeException
+     */
+    public function testLoadWithNotExistingFile()
+    {
+        $document = new Document();
+        $document->load('path/to/file', true);
+    }
+
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testLoadWithInvalidDocumentTypeArgument()
+    {
+        $document = new Document();
+        $document->load('foo', false, null);
+    }
+
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testLoadWithInvalidDocumentType()
+    {
+        $document = new Document();
+        $document->load('foo', false, 'bar');
+    }
+
     /**
      * @expectedException InvalidArgumentException
      */
@@ -51,12 +111,41 @@ public function testLoadHtmlFileWithInvalidArgument()
         $document->loadHtmlFile(array('foo'));
     }
 
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testLoadXmlWithInvalidArgument()
+    {
+        $document = new Document();
+        $document->loadXml(null);
+    }
+
+    /**
+     * @expectedException RuntimeException
+     */
+    public function testLoadXmlFileWithNotExistingFile()
+    {
+        $document = new Document();
+        $document->loadXmlFile('path/to/file');
+    }
+
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testLoadXmlFileWithInvalidArgument()
+    {
+        $document = new Document();
+        $document->loadXmlFile(array('foo'));
+    }
+
     /**
      * @expectedException InvalidArgumentException
      */
     public function testAppendChildWithInvalidArgument()
     {
-        $document = new Document('');
+        $html = $this->loadFixture('posts.html');
+
+        $document = new Document($html);
         $document->appendChild(null);
     }
 
@@ -184,6 +273,14 @@ public function testHtml()
         $this->assertTrue(is_string($document->html()));
     }
 
+    public function testXml()
+    {
+        $xml = $this->loadFixture('books.xml');
+        $document = new Document($xml, false, 'UTF-8', 'xml');
+
+        $this->assertTrue(is_string($document->xml()));
+    }
+
     public function testFormat()
     {
         $html = $this->loadFixture('posts.html');
@@ -204,6 +301,23 @@ public function testText()
         $this->assertEquals('foo', $document->text());
     }
 
+    public function testGetType()
+    {
+        $document = new Document();
+
+        $this->assertNull($document->getType());
+
+        $html = $this->loadFixture('posts.html');
+        $document = new Document($html);
+
+        $this->assertEquals('html', $document->getType());
+
+        $xml = $this->loadFixture('books.xml');
+        $document = new Document($xml, false, 'UTF-8', 'xml');
+
+        $this->assertEquals('xml', $document->getType());
+    }
+
     public function testIs()
     {
         $html = $this->loadFixture('posts.html');
@@ -239,7 +353,7 @@ public function testToElement()
         $this->assertInstanceOf('DiDom\Element', $document->toElement());
     }
 
-    public function testToString()
+    public function testToStringHtml()
     {
         $html = $this->loadFixture('posts.html');
         $document = new Document($html, false);
@@ -247,6 +361,14 @@ public function testToString()
         $this->assertEquals($document->html(), $document->__toString());
     }
 
+    public function testToStringXml()
+    {
+        $xml = $this->loadFixture('books.xml');
+        $document = new Document($xml, false, 'UTF-8', 'xml');
+
+        $this->assertEquals($document->xml(), $document->__toString());
+    }
+
     /**
      * @dataProvider findTests
      */
diff --git a/tests/fixtures/books.xml b/tests/fixtures/books.xml
new file mode 100644
index 0000000..e3d1fe8
--- /dev/null
+++ b/tests/fixtures/books.xml
@@ -0,0 +1,120 @@
+<?xml version="1.0"?>
+<catalog>
+   <book id="bk101">
+      <author>Gambardella, Matthew</author>
+      <title>XML Developer's Guide</title>
+      <genre>Computer</genre>
+      <price>44.95</price>
+      <publish_date>2000-10-01</publish_date>
+      <description>An in-depth look at creating applications 
+      with XML.</description>
+   </book>
+   <book id="bk102">
+      <author>Ralls, Kim</author>
+      <title>Midnight Rain</title>
+      <genre>Fantasy</genre>
+      <price>5.95</price>
+      <publish_date>2000-12-16</publish_date>
+      <description>A former architect battles corporate zombies, 
+      an evil sorceress, and her own childhood to become queen 
+      of the world.</description>
+   </book>
+   <book id="bk103">
+      <author>Corets, Eva</author>
+      <title>Maeve Ascendant</title>
+      <genre>Fantasy</genre>
+      <price>5.95</price>
+      <publish_date>2000-11-17</publish_date>
+      <description>After the collapse of a nanotechnology 
+      society in England, the young survivors lay the 
+      foundation for a new society.</description>
+   </book>
+   <book id="bk104">
+      <author>Corets, Eva</author>
+      <title>Oberon's Legacy</title>
+      <genre>Fantasy</genre>
+      <price>5.95</price>
+      <publish_date>2001-03-10</publish_date>
+      <description>In post-apocalypse England, the mysterious 
+      agent known only as Oberon helps to create a new life 
+      for the inhabitants of London. Sequel to Maeve 
+      Ascendant.</description>
+   </book>
+   <book id="bk105">
+      <author>Corets, Eva</author>
+      <title>The Sundered Grail</title>
+      <genre>Fantasy</genre>
+      <price>5.95</price>
+      <publish_date>2001-09-10</publish_date>
+      <description>The two daughters of Maeve, half-sisters, 
+      battle one another for control of England. Sequel to 
+      Oberon's Legacy.</description>
+   </book>
+   <book id="bk106">
+      <author>Randall, Cynthia</author>
+      <title>Lover Birds</title>
+      <genre>Romance</genre>
+      <price>4.95</price>
+      <publish_date>2000-09-02</publish_date>
+      <description>When Carla meets Paul at an ornithology 
+      conference, tempers fly as feathers get ruffled.</description>
+   </book>
+   <book id="bk107">
+      <author>Thurman, Paula</author>
+      <title>Splish Splash</title>
+      <genre>Romance</genre>
+      <price>4.95</price>
+      <publish_date>2000-11-02</publish_date>
+      <description>A deep sea diver finds true love twenty 
+      thousand leagues beneath the sea.</description>
+   </book>
+   <book id="bk108">
+      <author>Knorr, Stefan</author>
+      <title>Creepy Crawlies</title>
+      <genre>Horror</genre>
+      <price>4.95</price>
+      <publish_date>2000-12-06</publish_date>
+      <description>An anthology of horror stories about roaches,
+      centipedes, scorpions  and other insects.</description>
+   </book>
+   <book id="bk109">
+      <author>Kress, Peter</author>
+      <title>Paradox Lost</title>
+      <genre>Science Fiction</genre>
+      <price>6.95</price>
+      <publish_date>2000-11-02</publish_date>
+      <description>After an inadvertant trip through a Heisenberg
+      Uncertainty Device, James Salway discovers the problems 
+      of being quantum.</description>
+   </book>
+   <book id="bk110">
+      <author>O'Brien, Tim</author>
+      <title>Microsoft .NET: The Programming Bible</title>
+      <genre>Computer</genre>
+      <price>36.95</price>
+      <publish_date>2000-12-09</publish_date>
+      <description>Microsoft's .NET initiative is explored in 
+      detail in this deep programmer's reference.</description>
+   </book>
+   <book id="bk111">
+      <author>O'Brien, Tim</author>
+      <title>MSXML3: A Comprehensive Guide</title>
+      <genre>Computer</genre>
+      <price>36.95</price>
+      <publish_date>2000-12-01</publish_date>
+      <description>The Microsoft MSXML3 parser is covered in 
+      detail, with attention to XML DOM interfaces, XSLT processing, 
+      SAX and more.</description>
+   </book>
+   <book id="bk112">
+      <author>Galos, Mike</author>
+      <title>Visual Studio 7: A Comprehensive Guide</title>
+      <genre>Computer</genre>
+      <price>49.95</price>
+      <publish_date>2001-04-16</publish_date>
+      <description>Microsoft Visual Studio 7 is explored in depth,
+      looking at how Visual Basic, Visual C++, C#, and ASP+ are 
+      integrated into a comprehensive development 
+      environment.</description>
+   </book>
+</catalog>
\ No newline at end of file