Gas sorption and transport properties at 35 degrees C have been reported for a series of UV-irradiated films of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO). UV irradiation induced crosslinking in all films. The gas permeability was reduced upon crosslinking while significant increases in gas permselectivity were observed. The addition of benzophenone to the PPO films did not result in marked improvements in crosslinking or the resulting gas transport properties of the film.