This disclosure relates to a brain cooling and spinal cord cooling system, device or mechanism for use in military helmets, and in an adapted format in non-military helmets. The system is comprised of an inflatable pad, or a set of interconnected pads, attached to the interior surface of the helmet, together with a series of valves that allow cooling gases to be delivered from a high pressure canister. The use of different cooling gases permits the achievement and maintenance of cooling of the brain for 24 to 96 hours at a mild (36° C.) or moderate (33° C.-35° C.) brain hypothermia, which is 1.5° C.-4.5° C. below the core temperature.