Index: java/org/apache/poi/openxml4j/opc/internal/ContentType.java
===================================================================
--- java/org/apache/poi/openxml4j/opc/internal/ContentType.java	(revision 1518613)
+++ java/org/apache/poi/openxml4j/opc/internal/ContentType.java	(working copy)
@@ -17,7 +17,6 @@
 
 package org.apache.poi.openxml4j.opc.internal;
 
-import java.io.UnsupportedEncodingException;
 import java.util.Hashtable;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -68,7 +67,7 @@
 	/**
 	 * Media type compiled pattern for parameters.
 	 */
-	private final static Pattern patternMediaType;
+	private final static Pattern patternMediaType, patternMediaTypeParams;
 
 	static {
 		/*
@@ -90,8 +89,7 @@
 		 *
 		 * value = token | quoted-string
 		 */
-		// Keep for future use with parameter:
-		// String parameter = "(" + token + "+)=(\"?" + token + "+\"?)";
+		String parameter = "(" + token + "+)=(\"?" + token + "+\"?)";
 		/*
 		 * Pattern for media type.
 		 *
@@ -118,11 +116,9 @@
 		 * quoted-pair = "\" CHAR
 		 */
 
-		// Keep for future use with parameter:
-		// patternMediaType = Pattern.compile("^(" + token + "+)/(" + token
-		// + "+)(;" + parameter + ")*$");
 		patternMediaType = Pattern.compile("^(" + token + "+)/(" + token
-				+ "+)$");
+		        + "+)(;" + parameter + ")*$");
+		patternMediaTypeParams = Pattern.compile(";" + parameter);
 	}
 
 	/**
@@ -146,11 +142,17 @@
 			this.type = mMediaType.group(1);
 			this.subType = mMediaType.group(2);
 			// Parameters
+			// Be careful that java pattern matcher do not allow a multiple group capture
+			// only the last group is saved:
+			// http://docs.oracle.com/javase/6/docs/api/java/util/regex/Pattern.html#cg
+			// http://stackoverflow.com/questions/6138894/regex-to-read-multiple-parameters-of-unknown-multiplicity
+			// So a solution is to split pattern matcher in 2 parts... :-(
 			this.parameters = new Hashtable<String, String>(1);
-			for (int i = 4; i <= mMediaType.groupCount()
-					&& (mMediaType.group(i) != null); i += 2) {
-				this.parameters.put(mMediaType.group(i), mMediaType
-						.group(i + 1));
+			if (mMediaType.groupCount() >= 5) {
+			    Matcher mParams = patternMediaTypeParams.matcher(contentType.substring(mMediaType.end(2)));
+			    while (mParams.find()) {
+			        this.parameters.put(mParams.group(1), mParams.group(2));
+			    }
 			}
 		}
 	}
@@ -161,13 +163,12 @@
 		retVal.append(this.getType());
 		retVal.append("/");
 		retVal.append(this.getSubType());
-		// Keep for future implementation if needed
-		// for (String key : parameters.keySet()) {
-		// retVal.append(";");
-		// retVal.append(key);
-		// retVal.append("=");
-		// retVal.append(parameters.get(key));
-		// }
+		for (String key : parameters.keySet()) {
+		    retVal.append(";");
+		    retVal.append(key);
+		    retVal.append("=");
+		    retVal.append(parameters.get(key));
+		}
 		return retVal.toString();
 	}
 
Index: testcases/org/apache/poi/openxml4j/opc/TestContentType.java
===================================================================
--- testcases/org/apache/poi/openxml4j/opc/TestContentType.java	(revision 1518613)
+++ testcases/org/apache/poi/openxml4j/opc/TestContentType.java	(working copy)
@@ -84,10 +84,16 @@
     *  criteria of rule [01.2]
     * Invalid parameters are verified as incorrect in 
     *  {@link #testContentTypeParameterFailure()}
+    * @throws InvalidFormatException 
     */
-   public void testContentTypeParam() {
-      // TODO Review [01.2], then add tests for valid ones
-      // TODO See bug #55026
+   public void testContentTypeParam() throws InvalidFormatException {
+      // Reviewed [01.2], and added tests for valid ones
+      // See bug #55026
+      String[] contentTypesToTest = new String[] { "text/xml;key1=param1;key2=param2",
+              "application/pgp-key;version=\"2\"", "application/x-resqml+xml;version=2.0;type=obj_global2dCrs" };
+      for (int i = 0; i < contentTypesToTest.length; ++i) {
+          new ContentType(contentTypesToTest[i]);
+      }
    }
    
 	/**
@@ -95,8 +101,8 @@
 	 * parameters for content types.
 	 */
 	public void testContentTypeParameterFailure() {
-		String[] contentTypesToTest = new String[] { "mail/toto;titi=tata",
-				"text/xml;a=b;c=d", "mail/toto;\"titi=tata\"",
+		String[] contentTypesToTest = new String[] { "mail/toto;titi = tata",
+				"text/xml;a=;c=d", "mail/toto;\"titi=tata\"",
                 "text/\u0080" // characters above ASCII are not allowed
         };
 		for (int i = 0; i < contentTypesToTest.length; ++i) {