A new definition for instantaneous energy and drying efficiencies which can be integrated over the drying time to yield the cumulative efficiencies was proposed. This definition was then applied to experimental data for fluidized bed drying of corn, potato cubes and alumina beads, which represent hygroscopic, partially hygroscopic and nonhygroscopic materials with significant, moderate and negligible resistance to internal moisture flow, respectively. Further, the instantaneous drying and energy efficiencies were used to analyze literature data on batch and continuous drying in through-flow, crossflow and concurrent-flow configurations. It was shown that instantaneous indices may help to improve the overall energy performance by indicating modifications to the dryer design and specifying optimum operating parameters.