The cure behavior, thermal stability, and mechanical properties of diglycidylether of bisphenol A (DGEBA)/polysulfone (PSF) blends initiated by 1 wt % N-benzylpyrazinium hexafluoroantimonate as a cationic latent catalyst were investigated. The DGEBA/PSF content was varied within 100/0-100/40 wt %. Latent properties were studied through the measurement of the conversion as a function of the curing temperature, and the cure activation energy (E-a) was studied by the Kissinger method with a dynamic differential scanning calorimetry analysis. The thermal stabilities, largely based on the integral procedural decomposition temperature (IPDT) and de composed activation energy (E-t), were investigated by the measurement of thermogravimetric analysis. For the mechanical properties of the casting specimens, the critical stress intensity factor (K-IC) test was performed, and their fractured surfaces were examined with scanning electron microscopy. E-a, IPDT, E-t, and K-IC increased with PSF increasing in the neat epoxy resin up to 30 wt. %. However, there was a marginal decrease in the blend system in both the thermal and mechanical properties due to the phase separation between DGEBA and PSF. (C) 2000 John Wiley & Sons, Inc.