Coal is the largest energy source for electricity generation worldwide, at the same time, one of the largest anthropogenic sources of carbon oxides and other greenhouse gases released in the atmosphere. Coal gasification has emerged as a cleaner technology for producing fuel gases for power and heat production that reduces carbon dioxide emissions. The effect of operating conditions (temperature and pressure) on the coal gasification rate is very important regarding the design and operation of the coal gasifier. It is obvious that the rate of coal gasification reaction depends on the operating conditions, which are studied using the model of shrinking ashless (unreacted) spherical particles. The coal-to-coal gasification rate increases with the increase of temperature and partial pressure of CO2, but the total system pressure shows the negative effect on the coal-to-coal conversion. Keywords: Coal gasification, core shrinkage modelINTRODUCTIONThe reaction of carbon with CO2 is important in a variety of applications, including power generation through coal gasification and iron and steel smelting. Since several commercial gasifiers for IGCC operate at high temperature and high pressure (1200-1600 0C, 2.5 MPa). From the existing literature one can find information on the gasification characteristics of coal at atmospheric pressure [1-3]. However, only a few fundamental studies on the reactivity of coal gasification at high temperature and high pressure have been reported [4-7]. Coal gasification consists of two main reactions: coal pyrolysis and char gasification. Since the rate of gasification is much slower than that of devolatilization, the gasification characteristics or...... middle of paper ......on the X data versus time at the reaction temperature of 1300 0C, total pressure of 1MPa.3. CONCLUSIONS The gasification kinetics of an Indonesian sub-bituminous coal with CO2 is studied using an unreacted shrinking core model. The following results are obtained. The rate of gasification depends on the total pressure, temperature and partial pressure of the gasifying agents. The coal-coal conversion fraction decreases with increasing total pressure from 0.5-1.5 MPa at constant temperature and partial pressure of the gasifying agent. The coal-to-char conversion fraction will increase as the temperature increases from 900-1400 0C at constant total and partial pressure of the gas. The coal-to-char conversion fraction will also increase as the partial pressure of gasifying agent increases from 0.2-0.5 MPa at constant total pressure and temperature.