Abstract: Apparatus for incinerating and gasifying biomass material by employing a flight conveyor having an upper run traversing a horizontal, perforated upper grate and a lower run traversing a perforated lower grate which is parallel to and beneath the upper grate, the material being continuously deposited on the upper grate and urged continuously across it by the upper run in a bed wherein the material is pyrolyzed into char and combustible gas and then being deposited on the lower grate in a bed continuously urged by the lower run over a source of air beneath the lower grate so that the char is continuously oxidized by air from the source producing hot products which pass upwardly from the lower grate through the bed on the upper grate, filtering particulates from the products and providing heat for the pyrolysis, and then sequentially over a source of steam beneath the lower grate so that the char continuously reacts with steam from the source to generate water gas which is collected substantially unmixed with ot