The water diffusion process in a novolac epoxy resin (ER) was studied by 2D ATR-FTIR spectroscopy, the originally broad water OH bands in 1D-IR spectra can be effectively differentiated into three bands, located at 610, 3460, and 3240 cm(-1), respectively. The bands at 3460 cm(-1) (antisymmetric) and 3240 cm(-1) (symmetric) are assigned to the OH stretching vibration of water fully hydrogen-bonded with other water molecules, while the 3610 cm(-1) band could be attributed to the stretching vibration of water partially hydrogen-bonded with epoxy resin. The mechanism of the water diffusion process in EP is also discussed. (C) 2003 Elsevier Science B.V. All rights reserved.