In this paper an attempt is made to evaluate the convective mass transfer coefficient during drying of jaggery in a controlled environment. In this method, different masses of jaggery were used. The jaggery was dried in the roof type even span greenhouse with a floor area of 1.2 x 0. 8 m(2) in natural and forced convection mode at atmospheric pressure till it attained almost no variation in mass. The experimental data of mass evaporated, temperatures of jaggery, greenhouse room air and relative humidity were measured and the data used to evaluate the convective mass transfer coefficient by regression analysis. It was found that the convective mass transfer coefficient is a strong function of mass of jaggery, temperatures and relative humidity for a given size of greenhouse. (C) 2003 Elsevier Ltd. All rights reserved.