Quality of prunes is known to be influenced by the temperature and relative humidity of the dehydrator air, and by the time required for drying, long exposures to high temperatures at high humidities resulting in excessive caramelization and cooked taste. To determine the actual temperatures of prunes during dehydration, readings were made by thermocouples inserted at different points in prunes for three test runs at about 166 F, and relative humidities of 15, 27, and 43 per cent. To permit adapting the data obtained to commercial dehydrators, surface thermal conductances were computed. The vapor conductance at the surface was estimated from the thermal conductance, by employing the heat-mass transfer analogy. From the vapor conductance and the evaporation rate, the difference in vapor concentration required to move vapor from the prune surface to the air stream was calculated. Moisture movement within the prune was investigated by cutting the flesh of samples, removed after 3, 6, 10, and 16 hr drying, into two parts, that near the surface, and that near the pit.