Potentiometric sensors were developed for determining the concentration of the physiologically active polymer polyvinylpyrrolidone (PVP) with the use of its adduct with triphenylmethane and azodyes as electrode-active substances in plasticized membranes. The influences of electrolyte and pH of standard solutions on the electrode characteristics were determined. Polyvinylpyrrolidone determination in aqueous solutions of drug compounds, biological fluids and sewage was offered. The electrode selectivity factors were defined by fixed preventing ion method. The determined value of the selectivity factors varies in the n x 10(-1) interval.