Employing high surface area supports for catalytic hydrodechlorination can result in pronounced adsorption of reactants, intermediates and products. The influence of these sorption processes on the activity and selectivity upon 4-chlorophenol (4-CP) hydrodechlorination in aqueous solution has been studied using four commercial Pd/Al2O3 and Pd/AC catalysts at ambient pressure within the temperature range of 20–40°C ([4-CP]0=0.78–2.90mmolL−1, [catalyst]=1gL−1, 50NmLH2min−1). The adsorption capacity of the catalysts was independently evaluated. The Al2O3-based catalyst did not show any significant adsorption of those species whereas the activated carbon materials presented in all cases high uptakes (e.g. up to 2.4mmol4-CPgcat−1). In order to deduce true kinetic constants also for these catalysts, a kinetic model was developed, which accounts for the consecutive reaction and sorption processes in parallel. This expanded model resulted in a reasonable fit, can thus be used for comparison of different catalysts regardless their sorption capacity and allows predicting successfully the selectivity to the reaction products.