This paper concerns about selection of equilibrium moisture content-correlation of paddy, based on non-linear parameter estimation. The mathematical prediction of paddy sorption isotherm was developed for three-parameter EMC correlations such as that of Modified-Henderson, Modified-Chung-Pfost, Modified-Oswin, and Modified-Halsey. Moisture sorption experimental data were determined using a dynamic method at temperature 30 oC, 40 oC and water activity range of 0.07 - 0.75. The vapor pressure variations of air surrounding the grains were adjusted by varying sulfuric acid solution. Non-linear regression algorithms such as Simplex and/or Rosenbrock were used to fit the measured data to the EMC correlations. The study found that generalized correlation coefficient (R2) and the mean relative deviation were in the range of 0.85-0.99 and 1 % - 11 % respectively. In view of selection, it will be able to get the best equations among them to represent equilibrium moisture content of paddy grains. Furthermore, the Modified-Henderson correlation gives the best model for predicting the adsorption and desorption EMC for the range of temperature and water activity studied
