abstract: The object of research were roots of spring barley, variety Peyas (ukrainian variety). Plants growth was conducted in hydroponics, under controlled conditions, in nutrient medium with pH = 7, in the diurnal cycle of 16/8 hours (day-night), at temperatures of 20oC (day) and 16oC (night). At the beginning of the tillering stage, CdCl2 was added to the nutrient medium, in the concentration of 30 mg dm3 of nutrient medium. At the same time the pH of the solution was lowered to 4.5 (leaving the pH of the control unchanged at 7.0). Plants incubation period under stress conditions was 10 days. After that all the plants were collected and the surface charge of the roots was determined with the titration method. The titration was performed using the Titrino 702 MS titrator (Tetrohem). As the titrate 0.1 M dm-3. solution of NaOH was used, based on 1 M dm-3 NaCl solution. Under the influence of cadmium ions, the total variable charge (Q) of roots decreased, as did the cation-exchange capacity (CEC). No significant change was observed in the total acidity of the surface of the studied roots (pKapp av.), although the distribution functions of the dissociation constants showed a notable decrease of the expressive fraction pKapp~5-7. Decrease in the CEC can result in blocking of negative charge groups –COO- with Cd2+ ions. No significant differences were observed between roots growing at pH7 + Cd and at pH4.5 + Cd.