A hot air oven for heating food-loaded cartridges, each constituted by a stack of sealed trays comtaining pre-cooked meals nested within an open carton whose side walls have holes therein to admit heated air. The oven includes a rotating turn-table for supporting an annular array of such cartridges, the side walls of which define a hollow center core. A heater assembly produces heated air which is blown by a propeller into the hollow core, some of this air being forced through the holes of the cartons to heat the food in the trays. The remaining portion of the heated air passes through a flow passage below the cartridges to be drawn upwardly by the suction force of the propeller to create an air curtain around the array, thereby creating a toroidal flow pattern which envelops the annular array. The oven is divided by a shield placed within the hollow core into a hot zone and an extra hot zone, the cartridges of the turntable travelling cyclically through these zones. The temperature in the extra-hot zone is well above the service temperature to maintain a marked temperature differential between the heated air and the food even as it approaches its service temperature at which it can be dispensed to diners, thereby accelerating the heat-up rate at which the food is raised to its service temperature.