The work presents a study of molecular structure effects exerted by cycloalkylsubstituted acetylenes and ethylenes (cyclopropyl, cyclopentyl, cyclohexyl, phenyl) in hydrogenations on palladium and platinum supported catalysts. Experimentally evaluated values of parameters characterising the stability of an adsorbed complex (adsorptivity) and surface reaction rate (reactivity) were interpreted by means of molecular modelling. Trends in the adsorptivity parameters were correlated with the properties of frontier orbitals. (C) 2003 Elsevier B.V. All rights reserved.