Curing of N,N,N',N'-tetraglycidyldiaminodiphenylmethane with new curing agents like 3,3'-dichloro-4,4'-diaminodiphenylmethane and 2,2'-dichloro-4,4'-diaminodiphenylmethane in comparison with diaminodiphenylmethane and 4,4'-diaminodiphenylsulphone (DDS) was carried out using dynamic differential scanning calorimetry. The shelf life of various epoxy formulations was evaluated by the residual cure exotherm method. The glass-transition temperatures of cured epoxy formulations were determined using dynamic mechanical analysis. The mechanical properties such as the tensile strength, tensile modulus, flexural strength, and Izod impact strength were also evaluated and compared. The activation energy, frequency factor, and shelf life of chloro-substituted hardener formulations were high as compared to those of unsubstituted hardener formulations. The marginal differences in the glass-transition temperature, tensile strength, tensile modulus, and flexural strength and the small decrement in the Izod impact strength values were interpreted in terms of chlorine substitution.