The results of the study of complex formation through H-bond between the -C=O group of maleic anhydride (MA, electron-donor monomer) and the carboxyl group of acrylic acid (AA, electron-acceptor monomer) and the charge transfer complex between the double bond of MA and vinyl acetate (VA, electron donor monomer) using ultraviolet-visible spectroscopy (Uv-vis) and nuclear magnetic spectroscopy (H-1 NMR) methods are discussed. Maleic anhydride-methyl acrylate (MAc) monomer pair as a model system is also studied. The formation of two types of complexes in the MA-AA monomer system with further determination of their K-H and K-C values were studied using ultraviolet-visible spectroscopy (UV-vis) and H-1 NMR spectroscopy and the following well known equations of Benesi-Hildebrand, Ketelaar and Hanna-Aushbaugh, respectively. The formation of H-complex in the MA-AA system is confirmed by the analysis of electronic spectra of free monomers and their various mixtures (MAmuch greater thanAA) in dioxane at 25 degreesC. The equilibrium constant of the MA...AA charge transfer complex (CTC) formation was determined by H-1 NMR in p-dioxane and acetone at 25 degreesC. (C) 2003 Elsevier B.V. All rights reserved.