The variation of the quantity of poly(ethyleneglycol) adsorbed on TiO2, which follows a logarithmic law and is consistent with the exponential decrease in non-ionic polymer density observed by Hesselink at the solid-liquid interface, results in reduced zeta potential values. This decrease is uniquely due to the shift of the shear plane with a distance x equal to the thickness of the adsorbed polymer layer. A law, allowing the calculation of the thickness x from the adsorbed quantity of polymer Gamma and the zeta potential, was suggested. A coefficient Gamma alpha relating the adsorption alpha to x was defined.