Ok, I figured it out and documenting for those who come later. Below is an example of XA Datasource configuration for Postgres: postgres-xa-ds.xml Also you need to have Postgress .jar with org.postgresql.xa.PGXADataSource in your JBoss classpath. I am using postgresql-8.3-604.jdbc3.jar. I put it in my application lib directory. The database I am connecting to is legacy version 7.2 So I am not sure if I would have any problems with it, but it is a separate issue. <datasources> | <xa-datasource> | <jndi-name>DefaultDS</jndi-name> | <track-connection-by-tx/> | <xa-datasource-class>org.postgresql.xa.PGXADataSource</xa-datasource-class> | <xa-datasource-property name="ServerName">MyTestDBServer</xa-datasource-property> | <xa-datasource-property name="DatabaseName">MyDBName</xa-datasource-property> | <user-name>X</user-name> | <password>Y</password> | <!-- sql to call when connection is created --> | <new-connection-sql>select count(*) from pd_status</new-connection-sql> | | <!-- sql to call on an existing pooled connection when it is obtained from pool --> | <check-valid-connection-sql>select count(*) from pd_status</check-valid-connection-sql> | | <!-- corresponding type-mapping in the standardjbosscmp-jdbc.xml (optional) --> | <metadata> | <type-mapping>PostgreSQL 7.2</type-mapping> | </metadata> | </xa-datasource> | | ..... | | </datasources> View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4205389#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...