Multivariate curve resolution is applied to the study of Zn(II) complexation with anions of polymethacrylic acid and polyacrylic acid in aqueous solution containing 0.01 M KNO3. Data matrices obtained by different electrochemical techniques (normal pulse polarography, reverse pulse polarography, differential pulse polarography and differential pulse anodic stripping voltammetry) and for different ligand deprotonation degrees have been analysed individually and simultaneously by a procedure which consists of using several chemometrical techniques based on factor analysis : principal component analysis, evolving factor analysis and multivariate curve resolution with alternating least-squares optimization. These techniques were used to investigate the number of species present in the systems, their concentration profiles at increasing ligand concentration and their individual voltammograms together with the global (apparent) stability constants K and the ratio of diffusion coefficients of the individual species. The comparison of the results obtained by soft (model free) and hard (model postulated a priori) modelling for the systems investigated is discussed.