Figs. 4–6 show the changes in drying rate with drying time at different values of drying air temperature and fixed bed height. As can be seen, drying rate decreased continuously with drying time and decreasing moisture content. In these curves, there was no constant rate period in the drying of olive pomace. All the drying process occurred in falling rate period, indicating that the internal mass transfer has taken place by diffusion. Similar findings were reported for the drying of olive pomace and for other agricultural products such as organic tomato, green pepper, treated and untreated plums , figs, apple pomace and red bell pepper (var. Lamuyo). Also, as expected from Fig. 7, drying rate increased with increase in air temperature, thus reducing the drying time. This increase is due to the increase in heat transfer potential between drying air and olive pomace, thus enhancing the evaporation of water from the product.