An improved process for continuously producing oxygen-containing compounds by the oxo process from olefins, carbon monoxide and hydrogen at a pressure of 5 to 1000 bar and at a temperature of 50.degree. to 200.degree. C. in the presence of a metal of Group VIII and/or a compound thereof as catalyst is disclosed. According to the invention, the unreacted olefin carbon monoxide and hydrogen is passed to a high pressure reactor wherein unreacted olefin is reacted under oxo process conditions to form oxygen-containing compounds.