The gas permeabilities of CO2, N-2, O-2 and CH4 through a series of poly(aryl ether)s containing rigid terphenyl units in the main chain and pendent trifluoromethyl groups were determined at four different temperatures, 35, 45, 55, 65 degreesC and at I bar pressure. The effects of structural variations on permeability coefficients and selectivities for the gas pairs O-2/N-2, CO2/N-2, CO2/CH4, CO2/O-2, O-2/CH4 and CH4/N-2 are discussed. The polymers exhibited high permeabilities, but surprisingly low selectivities, considering the rather stiff polymer chains. The temperature dependence permeability/diffusion coefficients enables to calculate the activation energies for the permeation/diffusion process of different gases through these membranes. The gas permeability results were compared with analogous polymer structures containing pyridine and thiophene rings in the polymer backbone. The poly(arylene ether)s with terphenyl units showed higher gas permeabilities and comparable selectivities for a pair of gas in comparison to the analogous polymer with pyridine and thiophene elements. (C) 2003 Elsevier B.V. All rights reserved.