Analytical microparticle electrophoresis was used to characterize various polymer coatings known to control protein adsorption and related phenomena of biotechnical significance. The electrophoretic mobility of polystyrene latex microspheres and the electroosmosis associated with quartz capillaries were characterized over the pH range 2 to 11. Such characterization provides information related to surface modification. Aminopropylsilane and mercaptopropylsilane were shown to be effective sublayers for covalent attachment of hydrophilic polymers to quartz glass surfaces. Polyethyleneimine was similarly verified as an effective sublayer for polystyrene latex. Polymer coatings based on poly(ethylene glycol) and three polysaccharides, dextran, ethyl(hydroxyethyl)cellulose, and hydroxypropylcellulose, were found to significantly reduce capillary electroosmosis and microsphere electrophoretic mobility over a broad pH range. This reduction corresponds with the ability of these coatings to reduce protein adsorption and control surface wetting by aqueous polymer two-phase systems.