The article describes the synthesis and characterization of heterocyclic derivatives of stannanes obtained by reacting 1 mol of biguanide (B) with I mol of phenylethyltinclihydricle (PED) or phenylmethyltindihydride (PMD) or phenylbutyltindihydride (PBD) or butylmethyltin dihydride (BMD) and their use as curing agents for diglycidyl ether of bisphenol-A (DGEBA). The derivatives so obtained have been designated as BPED or BPMD or BPBD or BBMD. Structural characterization of the derivatives was done by elemental analysis and spectroscopic techniques, viz. IR, H-1 NMR, C-13 NMR, Sn-119 NMR. These derivatives were used as curing agents to investigate the effect of structure on the curing and thermal behavior of DGEBA. The curing behavior of DGEBA was investigated by differential scanning calorimetry in the presence of stoichiometric amounts of derivatives. A broad exothermic transition in the temperature range of 180-232 degrees C was observed in all the samples. Thermal stability of epoxy resin, cured isothermally, was evaluated by recording thermogravimetric traces in nitrogen atmosphere. The percent char yield was highest in case of resin sample, DBPMD. (C) 2007 Wiley Periodicals, Inc.