The synthesis of a new urethane acrylate monomer (UAM) from hexamethylene diisocyanate trimer (HDT) and 2-hydroxyethyl methacrylate was performed by classical condensation. Physicochemical and thermal characterization of UAM was investigated (<(Mn)over bar> = 1480 g mol(-1); T-g = -38 degrees C) and no secondary reactions were observed. The photoinitiated polymerization of UAM with 2,2-dimethyl-2-hydroxy acetophenone (Darocur 1173) as radical photoinitiator was studied by using thermal photocalorimetry at different temperatures. Photoinitiator concentration (0.15% w/w) and light intensity (2.7 mW cm(-2)) were kept constant. The maximum conversion was obtained at 70 degrees C. Above this temperature, thermal polymerization interfered with the photocalorimetric measurements.