Removal of trimethylamine (TMA) from the air is experimentally investigated by combining photocatalysis with a DBD plasma reactor, at ambient temperature and atmospheric pressure. Many parameters are investigated in this work, such as flowrate, inlet concentration, relative humidity of effluent, and specific energy of discharge. By combining non-thermal plasma and photocatalysis, a synergy effect on the removal efficiency of TMA has been observed under different experimental conditions. Moreover, we note that adding a photocatalyst in the zone of plasma inhibits ozone formation. The formation of by-products due to TMA removal is also studied. The identified and analyzed by-products are classified into four groups: intermediary products, carbon monoxide, carbon dioxide, and ozone and nitrogen oxides.