Densities, viscosities and water activities of aqueous solutions of polyvinylpyrrolidone have been determined experimentally at T = (298.15, 308.15, 318.15 and 328.15) K. From the density data, the apparent specific volume of polymer and the partial specific volume of polymer and water have been calculated. From the viscosity data, the viscosity and number average molecular weight of polymer have been calculated. From the water activity data, the vapour pressure of solutions has been calculated. Densities, viscosities and water activities have been correlated successfully with an general equation which takes into account the influence of the polymer concentration and the temperature. (C) 2004 Elsevier Ltd. All rights reserved.