Cryogenic air separation technology has been successfully employed for many years to supply oxygen for the gasification of a wide range of hydrocarbon feedstocks to generate synthesis gas for the production of fuels, chemicals and other valuable products. Examples include the conversion of liquid and solid refinery waste streams into hydrogen for use within the refinery along with the coproduction of electricity, and the growing interest in gas-to-liquids (GTL) processes which convert natural gas into synthetic crude oil, waxes and fuels. Recently, increased attention has been focused on methods of integrating the oxygen production process with the downstream hydrocarbon processing units to reduce facility cost or increase efficiency. A review of traditional and developing processes to generate oxygen is presented, along with integration schemes to improve the economics of these facilities.