Cyanate esters are a class of important thermally resistant polymers. To tailor their processability and thermomechanical properties, a series of cyanate ester blends based on a trifunctional novolac cyanate ester (HF-5), a di-functional bisphenol E cyanate ester (HF-9), and a reactive catalyst [2,2'-diallyl bisphenol A (DBA)] were formulated. The effect of the blend composition on the rheology and curing behavior of these cyanate ester blends and the corresponding thermal and mechanical properties of the cured cyanate ester blends was studied. The results showed that HF-5 contributed to good mechanical property retention at high temperatures because of its trifunctionality, whereas HT-9 imparted processability by reducing the viscosity and extending the pot life of the formulated cyanate ester blends at the processing temperature. On the basis of the results, an optimal cyanate ester blend suitable for resin transfer molding was determined: the HF-5/HF-9/DBA weight ratio of 80 : 15 : 5 exhibited good processability and thermomechanical properties. (c) 2006 Wiley Periodicals, Inc.