Ginger rhizomes of different thickness, microwave output power and sample load were dehydrated in a modified microwave oven, and effective moisture diffusivity was calculated. Among the various basic models considered, diffusion equation was most suitable to predict the drying behavior for the process conditions. Based on the interpretations, the constants and coefficients were rewritten in Arrhenius and logarithmic expressions for microwave power. The derived mathematical models were validated according to statistical parameters, viz. reduced chi-square, root mean square error, mean bias error and t-test values. The modified diffusion model explained the suitability of thin layer microwave drying behavior of ginger rhizome slices, yielding the highest R 2 of 0.9983. The effect of microwave drying on extraction of oleoresins with hexane as the solvent was in the range of 2.53-4.55%. Scanning electron microscopy and Fourier transform infrared spectroscopy revealed enhanced integrity of texture and functional groups by microwave treatment. © 2011 Wiley Periodicals, Inc.