A cryogenic freezing method uses a mixture of liquid nitrogen and liquid oxygen in amounts approximating the composition of atmospheric air to freeze food products. The mixture preferably includes 18% to 25% oxygen and the balance nitrogen, with small amounts of residuals which are commonly found in air. The present invention involves replacing a liquid carbon dioxide or liquid nitrogen cooling medium which is used in known cryogenic freezers with a liquid nitrogen and liquid oxygen mixture. The liquid nitrogen and oxygen mixture can be used according the present invention in many of the known freezers using liquid carbon dioxide or liquid nitrogen as a cooling medium, including tunnel freezers, spiral freezers, and immersion freezers. The use of a liquid nitrogen and liquid oxygen mixture improves the efficiency of a freezer because the cold vapors are not exhausted from the freezer. In addition, the leakage of vapors from the freezer into the room air will not create unsafe conditions for workers.