Alkynic and dienic substrates (C6-C10) in hexane and methanol were hydrogenated over a catalyst of 3% Pd on activated carbon at 20 °C and atmospheric pressure. The initial reaction rates were measured for the individual substrates; the hydrogenation rates of the olefinic substances formed were also determined if the hydrogenation was selective. The selectivities in competitive hydrogenations of substrate pairs were established and the relative adsorption coefficients of the substrates were calculated from them. The effect of the substrate structure and the solvent effect on the hydrogenation rate and relative adsorptivity are discussed for the alkynic and dienic substances studied.