Abstract: A curable composition comprising (A) an epoxy resin containing on average more than one epoxy group per molecule; (B) a compound of formula A[—X—CO—CH2—CN]n(1), wherein A is hydrogen or C1-C12 alkyl which is unsubstituted or substituted by one or more C1-C12 alkoxy groups, C1-C12 alkylcarbonyl groups, C7-C25 arylcarbonyl groups, hydroxyl groups, amino groups, C1-C12 alkylamino groups, C1-C12 dialkylamino groups, cyano groups or halogen atoms, or A is a bivalent aliphatic, cycloaliphatic, aromatic, araliphatic or heterocyclic organic radical, X denotes —O—or —NR1—, wherein R1 is hydrogen or C1-C12 alkyl which is unsubstituted or substituted by one or more C1-C12 alkoxy groups, C1-C12 alkylcarbonyl groups, C7-C25 arylcarbonyl groups, hydroxyl groups, amino groups, C1-C12 alkylamino groups, C1-C12 dialkylamino groups, cyano groups or halogen atoms, n is 1 or 2; and (C) a protected base in the form of an adduct or salt which is able to release a basic compound upon heating to a temperature greater than 70° C.