Presence of humidity in polluted gas streams is a key parameter to give a realistic view of a depollution process efficiency. With this in mind, the elimination of methanol by non thermal plasma in presence of a MnO2-CuO based catalyst and 35% relative humidity (20 degrees C, atmospheric pressure) was achieved. The reactor allows the treatment of low concentration pollutants (25-200 ppm) at weak residence time (0.36 s) in air at atmospheric pressure. Based on conversion rate and CO2 selectivity, a 5% MnO2/5% CuO/Al2O3 catalyst was selected within an array of catalysts prepared by different impregnation methods with various metal oxide ratios. The presence of humidity affected methanol conversion, ozone concentration and selectivities to by-products. Beneficial effects of humidity were observed on by-products elimination and CO2 selectivity despite a lower methanol conversion compared to dry air conditions.