The effects of ultrasound on the adsorption and desorption of phenol using activated carbon and polymeric resin was investigated. For adsorption in a batch adsorber, ultrasound was found to act like a mixer, improving the mass-transfer coefficient through cavitation and acoustic streaming. The mass-transfer coefficient was controlling for these systems. For desorption ultrasound was found to enhance the surface diffusivity. The surface diffusivity was controlling for these systems. The activation energy for surface diffusion was decreased by ultrasound. The intense localized heating and high-pressure shock waves caused by cavitation were found to be the major cause of the decrease. Effects on all parameters were found to be dependent on ultrasonic power. While ultrasound enhanced surface diffusion, its effect on equilibrium adsorption isotherms was found to be negligible for the systems studied.