This invention relates to a regenerating, hazardous waste gas fume and odor incinerator. The incinerator comprises a combustion chamber (12) and at least three heat exchanger regenerator beds (26, 28, 30) through which the waste gases pass selectively for preheating on their way to the combustion chamber and the processed, heated gases are passed through for cooling before exhausted. All three regenerator beds are cycled from a cooling position in which they absorb heat from the previously processed gases to a second position where they preheat waste gases en route to the combustion chamber to an inactive position where they do not receive gases either from the waste supply or from the combustion chamber. The waste gases, after being preheated, are directed to the combustion chamber through a plenum chamber (14) in which is located a combustion burner (16). The preheated waste gases are directed through the flame of the burner into the combustion chamber for ignition and for combustion therein. The incinerator has a flow control valve system (37, 39, 41, 43) and a computer controller (80) for cycling the regenerator beds as noted herein.