Novel triazole-based aluminum complex {O,O'-[4,5-P(O)Ph(2)tz]-AlMe(2) was studied as the catalyst for the ring-opening polymerization of caprolactone (epsilon-CL) in chlorobenzene. In the presence of methanol, isopropanol, and bifunctional poly(ethylene glycol), the catalytic system produced polymers with high conversion (81-85 %) but broader distribution (M (w)/M (n) = 1.5-1.8). The system of catalyst and benzyl alcohol produced relative monodisperse PCLs (M (w)/M (n) similar to 1.2) with defined molecular weight at 1/1ratio, 60 A degrees C and an initial concentration of epsilon-CL equal to 0.5 mol/L.