The isothermal curing process of bisphenol A epoxy resin with polyamine reagent (1,6-diaminohexane) was monitored in situ by using temperature-controlled Fourier-transform infrared (FTIR) and Fourier-transform near infrared (FTNIR) spectroscopy to elucidate the relative changes in functional groups during the curing reaction. It was shown that generalized two-dimensional correlation spectroscopy can provide new information about the mechanisms and kinetics of the curing process, and the band assignments for complex NIR spectrum associated with this system. The sequential order of relative changes in functional groups during the curing process was examined by generalized 2D correlation spectroscopy and NIR-IR hetero-correlation spectroscopy, and the details of the complex epoxy curing reaction involving both primary and secondary amino group were revealed. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 871-881, 2011