For identification and quantification of desired and undesired products during epoxy resin formation, polymerization of bisphenol-A with the stoichiometric excess of epichlorohydrin is carried out using catalytic excess of alkali. The reaction is monitored using Fourier transform infra-red (FT-IR) spectroscopy technique. Major undesired products are unreacted monomers (bisphenol-A and epichlorohydrin) and byproducts (chlorine and a-glycol substituted diglycidal ether of bisphenol-A), whereas the desired product is only diglycidal ether of bisphenol-A. Molar concentrations of epichlorohydrin, bisphenol-A, diglycidal ether of bisphenol-A, chlorine substituted resin, and a-glycol substituted resin in the polymerization mixture are analyzed and quantified using FT-IR characteristic frequency bands at 925, 3448, 1344, 773, and 3641 cm-1, respectively. For optimal determination of process parameters on polymerization, effect of temperature and alkali loading on epoxy polymerization is carried to maximize the yield of diglycidal ether of bisphenol-A with simultaneous minimizing the byproducts formation. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012