The purpose of this study is to evaluate the performance of after-treatment equipment and thermal storage devices for a combustortype CO2 generator. Since greenhouse ventilation is limited to minimize heat loss in the winter, the internal CO2 concentration may be reduced during the day, which limits the growth of horticultural crops. Therefore, CO2 generators are needed in greenhouses during the winter season. To reduce the levels of harmful exhaust gases produced by a CO2 generator, a metal particulate filter (MPF) catalyst has been selected as an after-treatment device, by considering back pressure and exhaust gas temperature. The CO and HC conversion rates of the MPF catalyst were 95% or higher, and the reduction efficiency for particulate matter was 43%. A thermal recovery device was used to recover 13% of the heat energy from the exhaust gas through heat exchangers installed on the exhaust line of the CO2 generator. The temperature of the exhaust gas was kept about 30°C, and 69% of the moisture within the exhaust gases was removed by condensing water, in order to minimize excessive humidity within the greenhouse.