The reactivity of uncatalysed and catalysed cyanate ester resin in solvent was investigated under room temperature conditions. At room temperature, the uncatalysed resin was non-reactive in the solvents while a triazine reaction leading to the polymerization of cyanate monomer occurred in the catalysed systems. The extent of reaction and the relative amounts of triazine depends on the time in solution, the concentration and type of catalyst, and the type of solvent. These reactions, that occur in solution at room temperature, can significantly reduce the glass transition temperature of the fully cured material.