Networks of diglycidylether of bisphenol A and 4,4′-diaminodiphenylmethane in the presence of imidazole up to 2,5 mole-% and in the absence of an accelerator were investigated. Differences in network density, glass transition temperature, thermal expansion coefficient above T g , and in the soluble part of the samples were found if an equimolar ratio of epoxy groups to amino hydrogen or an epoxy excess and different accelerator concentrations were used for network syntheses. Imidazole accelerates the conversion of epoxy groups, not only with amino hydrogen, but also with the hydroxyl groups formed. This is the reason for the differences in glass transition temperature, network density, thermal expansion coefficient, and soluble part between the samples investigated.