Equilibrium modeling has been used to predict the gasification process in a downdraft gasifier. The composition of the producer gas and, hence, the calorific value have been determined. The effects of initial moisture content in the wood and the temperature in the gasification zone on the calorific value have been investigated. The predicted values compare reasonably well with experimental data. The calorific value of the producer gas decreases with increase in moisture content in the raw material. The calorific value of the producer gas decreases as the gasification temperature increases in the range of temperatures investigated.