The object of the present work is to study the effect of drag-reducing additives like Polyox WSR 301 and sodium lauryl sulfate (anionic surfactant) on the rate of mass transfer at a vibrating horizontal screen, an electrochemical technique which involved measuring the limiting current of the cathodic reduction of potassium ferricyanide. Variables studied were the concentration of polymer and surfactant, frequency of vibration and amplitude of vibration. II was found that a decrease in the mass transfer coefficient occurs in the presence of surfactant which ranged from 3 to 61.8% depending on the concentration of the surfactant. The addition of a Polyox leads to a decrease in the mass transfer coefficient which ranged from 20 to 74.4% depending on the concentration of the polymer.