The radiation‐induced graft copolymerization of styrene with ethyl acrylate onto preirradiated polyethylene powder was carried out at 20°C. The grafting yield decreased in the following order: ethyl acrylate ≫ styrene > styrene–ethyl acrylate mixture. On the other hand, the amount of absorption of liquid monomers in polyethylene powder decreased as follows: styrene > styrene–ethyl acrylate mixture > ethyl acrylate. By kinetic analysis of the grafting yield and amount of absorption of monomers it was elucidated that the value Kp/Kt in an ethyl acrylate system (7.7 × 10−2) was much larger than those in styrene–ethyl acrylate systems and in a styrene system (ca. 1.0 × 10−2).