Osmotic dehydration and air-drying technology represent a technological alternative to reduce post-harvest losses of fruits. In this work, the influence of the osmotic solution composition of a ternary system (water/sugar/salt) was investigated for melon (Curcumis melo L.) dehydration. Sucrose, glucose and mannitol were used to formulate the osmotic solutions to study the effect of the sugar molecule in the osmotic dehydration process. The effect of the time spent in the osmotic solution on the water diffusivity was also studied showing that the diffusivity of water during the air-drying process increases as the fruit spends more time in the osmotic solution. The results that were obtained allowed to develop a mathematical model for the process of osmotic dehydration followed by air-drying and to estimate the process parameters of the osmotic dehydration and the air-drying processes. The model was further used to optimize the dehydration process aiming the reduction of the total processing time. The optimization showed the advantage of the use of the osmotic treatment to reduce the total processing time and the use of an osmotic solution with high sugar (70% w/w) and moderate salt (5% w/w) concentrations. (c) 2006 Elsevier Ltd. All rights reserved.