The effect of alumina nanoparticles on the viscosity and curing behavior of a bisphenol E cyanate ester monomer suspension was investigated by rheometry and differential scanning calorimetry. The viscosity was found to increase with solids content and was fit well by the Mooney equation. Cure experiments indicate that alumina particles catalyze the curing of the suspensions. The viscosity reduction achieved at high particle loadings by the addition of benzoic acid was also investigated by nuclear magnetic resonance. POLYM. ENG. SCI., 51:1409-1417, 2011. (C) 2011 Society of Plastics Engineers