A particle adhesion method for the determination of the isoelectric point (iep) of planar oxide surfaces in aqueous media is described. The experiment consists in measuring the rate of deposition of latex particles as a function of pH. We have measured the iep of fused silica, soda-lime silicate glass and thin films of different metal oxides: tin, aluminum, iridium and tungsten. We find our results in good agreement with data from the literature obtained with other experimental techniques.