A detailed analysis has been carried out to assess the role of reflective support on microwave heating of one-dimensional (1-D) slabs and 2-D cylinders for water and oil samples. The reflective supports are placed at the unexposed face for 1-D slabs, and the supports are the annular cylinders with specific radii for 2-D cylinders. A preliminary, analysis on microwave heating of samples has been shown via average power within a sample vs sample dimension diagram for various regimes. For 1-D water samples, the regime I corresponds to local maxima in average power for samples with supports, and regime H corresponds to maxima in power for samples without supports. For 1-D oil samples, the greater average power with supports during regimes I and H is observed. The enhanced power absorption is observed due to greater stationary field intensities, and the greater heating rates are due to the enhanced power deposition in samples with supports for specific regimes. For 2-D water samples, the reflective supports are found to be attractive for specific aspects ratios and power absorption can be enhanced by several magnitudes for thicker cylinder radii. The power absorption is found to be generally decreased due to supports for 2-D oil samples. (c) 2005 American Institute of Chemical Engineers.