Adducts formed by associating tertiary amines RN(CH3)(2) with haloboranes or pseudo haloboranes BX3 (X = Cl, NCS) were utilized as latent catalysts for curing epoxide-dicyandiamide compositions. Isothiocyanato borane adducts appeared as effective agents initiating the copolymerization reaction at 100 degrees C, whereas their chloro analogues principally produced an homopolymerization of the epoxide. The copolymerization was made possible by the tertiary amine, RN(CH3)2, released in the reaction medium by decomposition of the adduct. Compared to the chloro derivatives, the effectiveness of the isothiocyanato derivatives can be attributed to their ability to liberate the tertiary amine before the homopolymerization of DGEBA is initiated.