Experiments were carried out on a 2m diameter gas generator for a ceramics factory to study the effects of air-supply pressure, steam-saturation temperature and generator-gas exit temperature on fuel heating value. A total of 64 gasification experiments was performed using a standard coal mixture. Gaseous fuels with heating values ranging from 1100 to 1400 cal/liter were obtained. The heating value of the gas could be raised by up to 27% by maintaining the three process variables close to their optimum values, i.e. air-supply pressure = 43 cm of H2O, steam-saturation temperature = 55 degrees C, and generator gas-exit temperature = 160 degrees C.