Abstract: Food articles are heated by radiation in the near infrared wavelength range of 0.72 .mu.m to 2.5 .mu.m. Food articles can be thawed, heated or fully cooked direct from the frozen condition in this way. Hamburger patties are cooked in a conveyor cooker between rows of sources of such radiation. The sources are energized at half voltage during standby periods so that the conveyor is held at a temperature such that it has a searing effect on patties cooked by exposure to the radiation. Full energization is effected by operation of a switch in response to placement of a patty on the conveyor through a flap connected with the switch. A separate conveyor carries hamburger bun halves beneath a third row of the sources. In a static area employing sources of the radiation, reflector and screening arrangements provide even diffuse radiation in the heating zone and control of the heating effect is obtained by selective energization of the sources for selectively variable periods.