The electrohydrodynamical impedance on a rotating disk defined as the ratio of the mass-transfer rate response to a small sine-wave modulation of the angular velocity has been calculated for an Ostwald fluid. This impedance, expressed as a function of the modulation frequency suitably reduced by means of the rheological parameters, is then identical to the expression derived for a newtonian fluid. An excellent agreement was found between these calculations and experimental data obtained for a viscous flow of a polyethylene oxide solution of high molecular weight.