Cyanate esters are a class of thermal resistant polymers widely used as thermal resistant and electrical insulating materials for electric devices and structural composite applications. In this article, the effect of 2,2'-diallyl bisphenol A (DBA) on catalyzing the thermal curing of cyanate ester resins was studied. The curing behavior, thermal resistance, and thermal mechanical properties of these DBA catalyzed cyanate ester resins were characterized. The results show that DBA is especially suitable for catalyzing the polymerization of the novolac cyanate ester resin (HF-5), as it acts as both the curing catalyst through depressing the exothermic peak temperature (T-exo) by nearly 100 degrees C and the toughening agent of the novolac cyanate ester resin by slightly reducing the elastic modulus at the glassy state. The thermogravimetric analysis and dynamic mechanical thermal analysis show that the 5 wt % DBA-catalyzed novolac cyanate ester resin exhibits good thermal resistance with T-d(5) of 410 degrees C and the char yield at 900 degrees C of 58% and can retain its mechanical strength up to 250 degrees C. (c) 2006 Wiley Periodicals, Inc.