Abstract: Photopolymerization of MMA initiated by two a-hydroxy-a-alkyl-acetophenones (a-hydroxy-a, a-pentamethylene-acetophenone, 1-184 and a-hydroxy-a, a-dimethyl-p-isopropyl -acetophenone, D-1116) has been investigated. Results obtained show that their photo-initiation efficiencies are comparable with that of the benzoin ethers. The polymerization rates are directly proportional to the 0.4th power of concentration of initiators, and less dependent on the polarity of solvents. The values of K_p/K_t^1/2 are estimated to be 0.054 (1-184) and 0.053 (D-1116) respectivly.The above a-hydroxy-a-alkyl-acetophenones are qualified as good photoinitiators for the photopolymerization of acrylates to give the cured coating with good colour-stability.