Abstract: An autogenous portable apparatus is described for welding and oxygen cutting operations which uses a combustible gas fuel and oxygen derived from the decomposition of hydrogen peroxide flowing through a catalyst of lead chips. The catalyst is positioned to allow priming by initial quantities of hydrogen peroxide to be injected into the catalyst by the action of gravity. Once oxygen is formed the pressures thereof are fed back to the container holding the hydrogen peroxide thereby pressurizing the same and cause increasing quantities of oxygen to be produced until the desired level has been reached. Condensers are provided to condense the water vapor also formed in the conversion process to purify the oxygen prior to use thereof at a welding torch. A fluid control valve regulates the flow of the hydrogen peroxide at a rate inversely to the pressure of the oxygen to thereby maintain the pressure below a maximum predetermined value.