Acetals were formed under hydroformylation conditions of alkenes in alcohols as solvents. The hydroformylation process is combined with acetalization in a one-pot reaction leading to acetals as final products. These reactions sequences were catalyzed by the simple rhodium catalyst RhCl(3)center dot 3H(2)O. The effects of the addition of different types and amounts of phosphine and phosphite ligands were carefully studied in order to improve the regioselectivity of the reaction. (c) 2004 Elsevier B.V. All rights reserved.