Abstract: The present invention cleans gas produced from solid carbonaceous materials in a two stage gas producer. Second stage gas from the gas producer is passed through a first precipitator to remove oil mist and particulates from the second stage gas. First stage gas from the gas producer is passed through a cyclone to remove particulates from the first stage gas. The first stage gas from the cyclone is cooled and then mixed with the second stage gas from the first precipitator. The temperature of the gas mixture is maintained at least at the temperature of the second stage gas. The gas mixture is cooled to a temperature in the range of about 25.degree. F. to about 125.degree. F. above the water dew point of the gas mixture. The cooled gas mixture is subsequently passed through a second precipitator to remove oil mist and particulates from the gas mixture and to yield an industrial usable gas.