Polystyrene, PSt, (M(n) almost-equal-to 14 000) containing CCl3 end groups was obtained by free radical polymerization of styrene, St, initiated by decomposition of azo groups of 4,4'-azo-bis-(4-cyanopentane-trichloroacetylamide), ACPT, in dimethylformamide solution at 70-degrees-C. This polymer was used as initiator for free radical polymerization of methylmethacrylate, MMA. Free radical sites located at the end of PSt chains were generated photochemically (LAMBDA-inc = 436 nm) with the aid of Mn2(CO)10. St/MMA block copolymer containing 72 to 86 mol% MMA was obtained from the crude product after extraction of unreacted PSt with boiling cyclohexane. The results demonstrate that ACPT can be applied as a bifunctional initiator for the synthesis of block copolymers of type A(n)B(m) or A(n)B(m)A(n), consisting of monomers A and B prone to free radical polymerization.