Index: src/main/java/hudson/plugins/msbuild/MsBuildBuilder.java
===================================================================
--- src/main/java/hudson/plugins/msbuild/MsBuildBuilder.java	(revision 35868)
+++ src/main/java/hudson/plugins/msbuild/MsBuildBuilder.java	(working copy)
@@ -13,6 +13,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.util.Map;
+import java.util.HashMap;
 
 import net.sf.json.JSONObject;
 import org.kohsuke.stapler.DataBoundConstructor;
@@ -108,7 +109,16 @@
         if(normalizedTarget.trim().length()>0)
         	args.addTokenized(normalizedTarget);
         
-        args.addKeyValuePairs("-P:",build.getBuildVariables());
+        Map<String, String> buildVars = build.getBuildVariables();
+        HashMap<String, String> escapedBuildVars = new HashMap<String, String>();
+        for(Map.Entry<String, String> e: buildVars.entrySet()){
+            String key = e.getKey();
+            String val = e.getValue();
+            val = val.replace(",", "%2c");
+            val = val.replace("\"", "%22");
+            escapedBuildVars.put(key, val);
+        }
+        args.addKeyValuePairs("-P:", escapedBuildVars);
         
         //If a msbuild file is specified, then add it as an argument, otherwise
         //msbuild will search for any file that ends in .proj or .sln