A hot oil fryer for continuous frying duty in continuous food process lines has a frame, a cooking channel carried by the frame, a conveyor through the cooking channel having an upper food product carrying-run and a lower return runs, a bed of elongated heat exchanger tubes inside the cooking channel for circulating a thermal fluid, and a combustion-fired thermal oil heater supported by the frame off the floor for heating the thermal fluid which is circulated through the bed of elongated heat exchanger tubes. Preferably the cooking channel is elongated, as also preferably is the combustion-fired thermal oil heater carried, which is laid down to extend along a horizontal axis underneath the cooking channel. The combustion-fired thermal oil heater is fed either fuel-oil or a fuel-gas for combusting therein.