Abstract: A food product is prepared in a vertically slot-shaped oven space by being exposed to IR-radiation having a very short wave-length of the order of .mu.m simultaneously on two opposite vertical sides while being surrounded by a controlled air flow directed downwards. IR-radiation means are arranged adjacent the two opposite side walls delimiting the oven space. In a first embodiment the food product is held between two vertical net plates mounted on the inside of an oven door for being turned into the oven space when the door is shut. In a second embodiment the food product passes through the oven space while being held between two vertical parts of two endless net bands circulating downwards through the oven space.