Atmospheric osmotic dehydration experiments were carried out with apple (Granny Smith var.) slices (20 and 30 mm thick) and sucrose-water osmotic solutions, 65% (why), at different temperatures (20 degrees C, 30 degrees C, 40 degrees C and 50 degrees C). After treatment, serial cuts, 1.5 mm thick, were obtained to determine water and sugar content profiles. Values of diffusion coefficients were obtained in situations of developed and non-developed profiles. An ＇advancing disturbance front＇ mechanism was proposed. The results showed that full development of concentration profiles takes several hours depending on temperature and sample thickness (more than 34 h for a sample of 30 mm thick at 30 degrees C).