A non-thermal dielectric barrier discharge (DBD) plasma reactor was integrated with an M/SBA-15 (M = Pd, Pt, Ag and Au) catalyst, where metal reduction was achieved by H2 plasma treatment. Subsequently, the plasma-catalytic combination mode was tested for the methane partial oxidation reaction to liquid oxygenates, and the results were compared with the plasma-only system in terms of reactant conversion, energy efficiency and product distribution. The results from the characterization of the catalysts confirmed that the plasma treatment improved the surface characteristics of the catalysts and also modified or expanded the discharge on the catalytic surface. The plasma energetic species generally helped to flatten the metal nanoparticles over the support surface, which resulted in a better dispersion with the formation of smaller nanoparticles. A total liquid selectivity of 70% was achieved for the plasma-treated Pt/SBA-15-DBD system with almost 12% CH4 conversion compared to 58% total liquid at 7% CH4 conversion with the plasma-only system. © The Royal Society of Chemistry.