In this study, drying kinetics of kiwifruit are investigated experimentally and theoretically under varying drying conditions. Experiments are conducted using air temperatures at 35, 45, 55 and 65 degrees C, mean velocities at 0.3, 0.6 and 0.9 m s(-1) and, relative humidity values at 40%, 55%, 70% and 85%. Initially, sorption isotherms of the dried kiwifruit slices are determined for different temperatures and equilibrium relative humidity values. The values of the moisture diffusivity, D-eff are obtained from the Fick's diffusion model. The effects of the governing drying parameters on the vitamin C content as well as on the total drying time are determined. The experimental moisture data were fitted to some models available in the literature, mainly the Henderson and Pabis model, the Lewis model and the two-term exponential model and, a good agreement was observed. In addition, it is disclosed that increasing drying air temperature causes more loss in vitamin C in the dried fruits while degradation of vitamin C is reduced with increasing relative humidity of drying air. (C) 2008 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.