The kinetics of aqueous polymerization of N-vinylpyrrolidone (N-VP) was carried out using potassium peroxidiphosphate-Ag+ system under nitrogen atmosphere at 25-degrees-C. The rate of polymerization was directly proportional to the concentration of the N-vinylpyrrolidone and showed a half-order with respect to the concentration of the peroxidiphosphate (H2P2O82-) and Ag+ ions. The value of k(p)(k(t))1/2 was computed and its value found to increase on increasing the temperature of the reaction mixture. The energy of activation (E(a)) was found to be 65.8 +/- 0.1 kJ mol-1 within the temperature range from 20 to 50-degrees-C. Viscometric average molecular weight of polyvinylpyrrolidone was determined by measuring intrinsic viscosity of the polymer samples collected at different kinetic conditions. The effect of various additives was also studied. A suitable mechanism of polymerization has been proposed and a reaction rate law was derived considering experimental results.