Abstract: A compact chlorine generation device generates chlorine and usually ozone. The device is water cooled. A power transformer has a housing thereabout in heat conductive contact therewith. A highly heat conductive metal frame is attached in direct efficient heat conductive relation with the housing. The frame has a conduit therethrough generally adjacent to the housing. A metal block has a semi-conductor power rectifier held in a cavity therein and in thermal contact therewith. The block is attached in direct heat conductive relation with the frame. A coolant is flowed through the conduit thereby cooling the transformer and the rectifier. A chlorine generating electric cell has an anode and a cathode which are connected to the respective DC output poles of the rectifier. The coolant which exits the conduit is led to the cell wherein it serves as the electrolyte.