This article describe the influence of phenolphthalein poly (ether ketone) (PEK-C) on the cure behaviors and thermal properties of the diglycidyl ether of bisphenol A (DGEBA) epoxy resin with cyanate ester as curing agent. The curing kinetics and reaction pathways were monitored using dynamic differential scanning calorimeter and Fourier transform infrared spectroscopy. The dependence of activation energy on the conversion degree for all the studied systems was calculated in the light of Ozawa-Flynn-Wall method. Furthermore, the thermomechanical properties and the thermal stability of the cured resins were also evaluated by dynamic mechanical analysis and thermogravimetric analysis, respectively. Conclusions can be drawn as follows: the main reaction pathways did not vary with the inclusion of PEK-C, but the reaction rate of the blend was found to be higher than that of the neat epoxy. The glass transition temperature of the blend was not changed by the addition of PEK-C, while the initial decomposition temperature slightly decreased with increase in PEK-C content. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2590-2596, 2009