A process and system for low NOx cogeneration to produce electricity and useful heat. Fuel and oxygen are provided to an internal combustion engine (10) connected to drive an electric generator (9), thereby generate electricity. An exhaust stream is recovered from the engine. Fuel is added to the exhaust stream to create a fuel-rich mixture. The fuel enriched stream is provided to an afterburner (18) to provide a heated oxygen-depleted stream. The oxygen-depleted stream is cooled in a first heat exchanger (22). Conversion oxygen is admixed with the cooled stream which is then passed over a catalyst bed (25) under overall reducing conditions. The stream from the reducing catalyst bed is cooled and air is added to produce a further cooled stream and the further cooled stream is passed over an oxidizing catalyst bed (26) to oxidize remaining combustibles.