Adsorption and variable surface charge of young sieve roots of triticale and wheat after 24 h aluminium stress were studied using water vapour adsorption isotherms and potentiometric titration data. Root surface areas increased and the amount of variable surface charge decreased after stress. Functions of adsorption energy distribution showed a decrease of the amount of highly energetic surface adsorption centres and an increase of the low energetic ones, which lead to a lowering of average water vapour adsorption energy of the stressed roots. Distribution functions of apparent surface dissociation constants showed a decrease of surface acidity. The observed changes were more pronounced for the roots that were not able to grow further after stress.