AbstractA kinetic analysis of the radiation‐initiated copolymerization reactions of 2‐hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), and methacrylic acid (MAA) from water, methanol (MeOH), N,N‐dimethylformamide (DMF), dimethysulfoxide (DMSO), and combinations of these solvents with irradiated fibrous cellulose I and II was made. The maximum extent of copolymerization of HEMA and HPMA with irradiated cellulose occurred from water solutions. When organic solvents were added to the water solution, while the concentration of monomer was kept constant, the extent of copolymerization decreased. The maximum extent of copolymerization of MAA with irradiated cellulose occurred from mixtures of MeOH (15–30 vol‐%) and water (85–70 vol‐%) solutions rather than from water. After initiation of the copolymerization reactions, they were apparently diffusion controlled and exhibited second‐order kinetics. The relative concentrations of grafted polymer and homopolymer formed with irradiated cellulose from aqueous solutions depended primarily on the concentration of water in the solutions. From MeOH (60 vol‐% or less)–water (40 vol‐% or more) solutions, about 60% of poly(MAA) formed was apparently grafted polymer; from solutions containing less water, the fraction of grafted polymer decreased to about 40%.