In this paper, we describe the hydroformylation of terminal and internal olefins to terminal aldehydes using a catalyst system of rhodium and BIPHEPHOS. According to industrial processes, the catalyst concentration lies in a range from 0.01 to 0.001 mol%. The conversions are, depending of the substrate, up to 99% and yields up to 86% of the aldehydes can be found. The ratio of linear to branched products is up to 99:1. (c) 2005 Elsevier B.V. All rights reserved.