The wear characteristics of PTFE and PTFE based composites, graphite filled PTFE, and glass fiber filled PTFE, in the hydrogen atmosphere were studied as polymeric sealing materials for hydrogen energy systems. The wear behavior of graphite filled PTFE was influenced by the gaseous environment as unfilled PTFE. The specific wear rate of graphite filled PTFE was higher in hydrogen compared with argon gas if the contact pressure and the sliding speed were relatively low. However, the specific wear rate in hydrogen became lower than that in argon with increasing the PV value. The wear of glass fiber filled PTFE was less sensitive to the gaseous environment. This is an abstract of a paper presented at the World Tribology Congress (Kyoto, Japan 9/6-11/2009).