Cu(OAc)2 was assessed to be a good catalyst for the bulk ring opening polymerization of lactides. These polymerizations are highly controlled leading to the formation of polymer with expected number average molecular weights and narrow molecular weight distribution. This method may be used to synthesize polymers with different end terminal groups. The over all process is green, since these polymers being biodegradable and the system is independent of solvents. © 2011 Elsevier B.V. All rights reserved.