The homogeneously catalyzed hydroformylation of linear olefins was investigated at pressures ranging from 7 to 550 MPa. A change in the selectivity was observed, which was reflected by a change of the product distribution. At high-pressures, increased yields of aldehydes were also obtained from the hydroformylation of sterically hindered olefins. (C) 2004 Elsevier B.V. All rights reserved.