Abstract: An apparatus for devulcanizing vulcanized rubber or crosslinked polymeric material has an ultrasonic exposure portion including a body forming an exposure channel through which particles of the material flow and an ultrasonic generator including a horn extending generally transverse to the direction of the material flow. The apparatus also has a preconditioning portion for feeding the particles to the ultrasonic exposure channel. The method for devulcanizing vulcanized rubber or crosslinked polymeric material comprises the steps of preconditioning and feeding particles of the material, including heating the particles; feeding the particles through a pressurized exposure channel; and exposing the particles to ultrasonic energy within the exposure channel with an ultrasonic wave propagated in a direction transverse to the direction of the channel to effect devulcanization by breaking chemical bonds in the material.