The gas transport properties for H-2, O-2 and N-2 in five random copolymers of polypyrrolone and polyphenylquinoxaline and the two homopolymers have been determined at 30 degrees C and 1 atm. The polypyrrolone exhibits higher selectivity with lower permeability, whereas polyphenylquinoxaline shows lower selectivity with higher permeability. The permeability of the copolymers increase with increasing polyphenylquinoxaline content but the selectivities decrease. Temperature dependence of the gas permeability is reported for one copolymer, which is the same as in other glassy polymers.