Competitive catalytic hydrogenation of acetylenecarboxylic acid dimethylester, fumaric acid diethylester and maleic acid diethylester, respectively, were studied in liquid phase on palladium and platinum catalysts. Kinetic parameters evaluated from hydrogenation of individual substrates and of binary systems in competitive arrangements allowed a discussion of coadsorption effects of the alkenic bond on the reaction course of the alkynic substrate. (C) 2003 Elsevier Science B.V. All rights reserved.