After several tries getting a java application running on Firefox v3.6.10 on my Ubuntu 10.04, here is how I finally got it up & running. The standard procedurre is as follows: 1. Download and install the Linux version of the Java software. 2. Create a simbolic link to your (will depends on Firefox version): A) Firefox version earlier than 3.6 Create a simbolic link to the plugin: your_firefox_plugin_dir# ln -s /your_path_to_java/plugin/i386/ns7/libjavaplugin_oji.so libjavaplugin_oji.so B) Firefox 3.6 and later need the Next-Generation Java Plug-In ( details ) Run this command in the plugins directory of your Firefox installation to create a symbolic link to the Java plugin: your_firefox_plugin_dir # ln -s /usr/your_path_to_java/lib/i386/libnpjp2.so libnpjp2.so 3. Test it Open Firefox and type about:plugins on the address bar. You should see the plugin installed along with some other information. More... MozzillaZine Knowledgebase: Java Manual Installation and ...