Abstract: System and method for processing extruded sponge rubber products and the like by simultaneously heating the products with microwave energy and impinging jets of high velocity hot air on the products. In one disclosed embodiment, the extruded sponge rubber parts are passed through a series of impingement rings in a microwave cavity, and each of the rings has a plurality of inwardly facing nozzles for directing jets of air in a radial direction toward the parts. Rollers transport the parts between the rings and can be driven at different speeds to accommodate elongation of the rubber parts as they expand. The microwave power is applied in pulses to provide more uniform heating of the parts, and the time base of the pulses can be changed without having to readjust the on-time of the pulses to maintain the on-time as a given percentage of the time base.