Abstract: Exothermic reacting chemical oxygen generators are heat insulated with a hydrate to protect the user. The hydrate, when heated by the generator releases water which is vaporized and allowed to escape to a zone which will not be grasped by the user or is absorbed in a surrounding inert insulation layer where it can condense and revaporize as the heat wave passes through the surrounding inert insulation. The generator is preferably in the form of a disposable canister such as a tin can containing an oxygen generating chlorate candle and means for igniting the candle. A mask or cannula carrying cap is snapped on the can and has mechanism for piercing the can and activating the ignition means to flow oxygen to the mask or cannula.The preferred insulation includes a hydrate salt layer sandwiched between metal foil-backed refractory fiber blankets and covered with a sleeve.