If I understand right, you are tyring to lookup an EJB which is deployed in JBoss, from Weblogic. If so, then you have to pass the INITIAL_CONTEXT_FACTORY (org.jnp.interfaces.NamingContextFactory) and PROVIDER_URL (jnp://IP:1099 where IP is the IP/hostname of JBoss server and 1099 should be replaced by the JBoss Naming port) corresponding to the JBoss AS server. Also you will have to place the appropriate JBoss specific client jar files (available in JBOSS_HOME/client folder) under Weblogic classpath.