The ionic [Ti-3(mu(3)-OPri)(2)(mu-OPri)(3)(OPri)(6)][FeCl4] halo-alkoxide (A) was investigated for its activity towards the bulk polymerization of rac-lactide (rac-LA) and -caprolactone (-CL) in various temperatures, monomer/A molar proportions, and reaction times. The reactivity of A in the ring-opening polymerization (ROP) of both monomers is mainly due to the cationic [Ti-3(OPri)(11)](+) unity and proceeds through the coordination-insertion mechanism. Molecular weights ranging from 6,379 to 13,950 g mol(-1) and PDI values varying from 1.22 to 1.52 were obtained. Results of ROP kinetic studies for both -CL and rac-LA confirm that the reaction rates are first-order with respect to monomers. The production of poly(-caprolactone) shows a higher sensitivity of the reaction rate to temperature, while the polymerization of rac-LA is slower and more dependent on the thermal stability of the active species during the propagation step. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2509-2517