The effect of methane on the conversion of HFC-134a (CF3CH2F) in a dielectric barrier discharge non-equilibrium plasma reactor was examined. Reactions were conducted in an argon bath gas and in the absence of oxygen and nitrogen. The products of the reaction include H-2, HF, CHF3, CH2F2, C2H6, C3H8, C2H3F, CHF2CHF2, C2H4F2, C3H7F as well as a polymeric solid deposit. The polymeric materials are predominantly fluorine containing random copolymers, which can be categorised as fluoropolymers, constituted from various functional groups including CF3, CF2, CHF, CHF2, CH2F, CH2 and CH3. While the presence of methane in the feed stream reduces the conversion level of CF3CH2F, it also modifies the polymer architecture. The addition of 1.25% methane with 12.5% CF3CH2F in an argon bath gas at 100 cm(3) min(-1) feed rate reduces the conversion of CF3CH2F from 74.5% to 46.8% and increases the formation of HF from 1500 mu mol h(-1) to 2640 mu mol h(-1). The effect of methane addition on the electrical discharge and the reaction pathways are discussed. (C) 2015 Elsevier B.V. All rights reserved.