A high-temperature, high-pressure process used for the production of aldehydes and alkenes from the catalytic reaction between alkanes, carbon monoxide, and hydrogen. The process was invented in Germany in 1938 by O. Roelen, although modified many times since, and is used in the production of fragrances and intermediates for the production of detergents. The name is derived from the German oxierung meaning ketonization. It is also known as oxo synthesis or hydroformylation.