In this work, the reversible addition-fragmentation chain transfer (RAFT) polymerization of vinyl acetate (VAc) was successfully performed at room temperature using Co-60 gamma-irradiation as the initiation source. Under the dose rate of 10 Gy/min irradiation, the polymerization proceeded smoothly and converted approximately 90% of the monomer within 7 h. The molecular weight distribution (M-w/M-n) remained narrow (M-w/M-n < 1.35) up to 90% conversion. Compared to AIBN-initiated RAFT polymerization at 60 degrees C, (CO)-C-60 gamma-irradiation-initiated RAFT polymerization is a technique that can better control the molecular weight, especially at high conversion. The H-1 NMR spectra and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry confirmed that most of the chain ends of poly(VAc) (PVAc) from gamma-irradiated RAFT polymerization were living and can be reactivated for chain-extension reactions. The microstructures of PVAc from Co-60 gamma-irradiated RAFT polymerization (almost head-to-tail addition) and AIBN-initiated RAFT polymerization (5% tail-to-tail addition) were different, as revealed by the C-13 NMR spectra. For the first time, Co-60 gamma-irradiation was used as an initiation source for RAFT polymerization of VAc at room temperature. (C) 2011 Elsevier Ltd. All rights reserved.