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The effects associated to the introduction of acoustic energy into a medium may influence food drying processes due to the reduction of mass transfer resistance. In particular, power ultrasound may be useful for drying heat sensitive materials since it permits drying to be increased without significantly heating the material. The main aim of this work was to determine the influence of power ultrasound on lemon peel drying, by evaluating the effect of the ultrasonic power applied. Lemon peel, a by-product of lemon processing, is a source of valuable heat sensitive products. An aluminium vibrating cylinder, which is able to create a high intensity ultrasonic field in the gas medium, was used as drying chamber. The cylinder is driven at its centre by a power ultrasonic vibrator at 21.7 kHz. Convective drying kinetics of lemon peel slabs (thickness 7± 1 mm) were carried out at 40 ºC and 1 m/s. Experiments were performed without ultrasound application (AIR) and also by applying different ultrasonic power levels: 10, 20, 30, 40, 50, 60, 70, 80 and 90 W. A diffusion model considering external resistance to mass transfer was used to model drying kinetics. Results showed that drying kinetics of lemon peel were affected by the application of power ultrasound. Drying rate increased as the ultrasonic power applied got higher. From the modelling, a linear relationship was found between effective diffusivity (D e , m 2 /s) or mass transfer coefficient (k, kg w/m 2 /s) and the ultrasonic power applied (W). Therefore, power ultrasound increased both external and internal resistance to mass transfer, the improvement being proportional to the ultrasonic power applied.