The graft copolymerization of N-vinyl pyrrolidone (N-VP) onto cellulose was carried out with a cobalt acetylacetonate complex Co(acac)(3) as an initiator under a nitrogen atmosphere at 50 +/- 0.1 degreesC. The graft yield percentage (%G) obtained as a function of the concentrations of N-VP and Co(acac)(3) and the temperature was used to calculate various other grafting parameters and the grafting rate dependence on the concentrations of monomer, Co(acac)(3) and reaction temperature. The energy of activation (DeltaE(a)) for the grafting of N-VP onto cellulose was 22.7 kJ/mol within 40-60 degreesC. The molecular weights of the grafted chains and homopolymers were determined viscometrically with a Ubbelohde-type viscometer. Graft yield (%G) in the presence of various additives such as sodium lauryl sulfate, cetyltrimethylammonium bromide, and methanol was studied, and the results are suitably explained. On the basis of the experimental results, a reaction scheme for graft copolymerization is proposed, and a kinetic rate expression is presented.