The influence of acetate groups contained in polyvinyl alcohol (PVA) and its molecular weight on the electrical properties of the Al2O3-polymer solution interface were examined. The main factors, having influence on the zeta potential and surface charge changes of Al2O3, were learned. It was shown that the change of the ion structure in the Stern layer depends considerably on the number of acetate groups (degree of hydrolysis) of the PVA macromolecule and on the conformation of the polymer chain. By the comparison of the determined values of the diffuse layer and surface charges a probable mechanism was proposed, leading to zeta potential changes as a function of pH of the solution and PVA molecular weight. The calculated thickness of the adsorption layers of PVA on the surface of Al2O3 confirmed the essential effect of acetate groups of PVA on its conformation at the surface layer of the adsorbent.