Trimethylamine, one component of malodorous gases from crematory emission, was removed by a corona-discharge reactor to apply the reactor to purification of crematory emission gas. The effects of discharge current and coexisting oxygen or water vapor on the removal efficiency of trimethylamine were investigated. Although trimethylamine was not effectively removed from nitrogen by corona discharge, the removal efficiency was improved greatly by mixing oxygen or water vapor. The amounts of reaction by-products generated were extremely large at high discharge current in the removal from a nitrogen-oxygen mixture. On the other hand, the by-products were greatly suppressed by mixing water vapor. The deposit on the anode of the reactor was analyzed by a thermogravimetry. As a result, trimethylamine was found on the anode surface as the deposit of carbon compounds which have high boiling point.