The water effective diffusion coefficient of sardine sheets during osmotic dehydration was determined, assuming this process to be governed by Fickian diffusion. Osmotic dehydration of sardine sheets (20.1 x 15.0 x 6.4 mm(3)) was carried out over five concentrations (0.15, 0.18. 0.21, 0.24 and 0.27 kg NaCl/kg) and temperatures between 30 and 38 degrees C of osmotic solution. The water effective diffusion coefficient ranged approximately from 2.084 x 10(-12) to 3.015 x 10(-12) m(2)/s. Temperature sensitivity of water diffusion coefficient increased (p < 0.05) with increasing brine concentration below 0.24 kg NaCl/kg. This temperature sensitivity was changed, decreased (P < 0.05) at brine concentrations equal or higher than 0.24 kg NaCl/kg. The water effective diffusion coefficient was empirically correlated with concentration and temperature of osmotic solution. A high degree of correlation was observed between predicted and experimental values of the water effective diffusion coefficient (R-2 = 0.909). (c) 2006 Elsevier Ltd. All rights reserved.