In this study, we investigated the application of the luminescence spectroscopy technique in steady-state conditions to study glass fiber-epoxy F161 prepregs. We conducted this study by comparing the results obtained from the intrinsic fluorescence with Fourier transform near infrared spectroscopy. The extrinsic fluorescence of 9-anthroic acid (9-AA) was also used. Fourier transform infrared spectroscopy was also used to characterize the epoxide resin. The prepregs containing 9-AA and those that did not were heat-treated at 177 C (F161) for 1100 min at a 2 degrees C/min heating rate. The results obtained by both methods indicated that the crosslinking reaction could be monitored by analysis of the spectral changes of the emission bands of the prepreg and 9-AA. The intrinsic emission at 320 nm was attributed to the fluorophore group containing the epoxy ring and was used to calculate the conversion degree. The photophysical behavior of the 9-AA probe indicated a reduction of free volume of the polymeric matrix with curing process. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 664-671, 2010