Mass transfer coefficient, h. during frying of sweetpotato was estimated by inverse simulation of the frying process using finite element method and experimental data on temperature and moisture content change in the product. Frying with three disc sample sizes (diameter of 2.5, 3.5 and 4.0 cm and all of 1 cm thickness) were simulated at oil temperatures of 150, 160, 170 and 180 degrees C for 5 min. The range of maximum h. reached was 4 x 10(-6) -7.2 x 10(-6) m/s. Both h and h(m) during the process increased with increase in frying oil temperature but decreased with increase in sample size. No general correlation was established between h and hm due to its insignificancy. Furthermore, there was discrepancy between the periods during frying when the maximum h and hm appeared. However, a correlation was established between maximum h and maximum hm and also between maximum h and the corresponding h. at that time. (c) 2008 Elsevier Ltd. All rights reserved.