A kinetic study of the hydrogasification of Illinois #6 coal was carried out using a ternary (43.5 mol% Li2CO3-31.5 mol% Na2CO3-25 mol% K2CO3) and a binary (29 mol% Na2CO3-71 mol% K2CO3) eutectic system. Hydrogasification experiments were carried out in a high-pressure, high-temperature differential fixed-bed gasifier unit to evaluate the product inhibition effect of H-2 on the overall steam gasification kinetics. The overall gasification rate was found to decrease with an increase in the H-2 partial pressure. It was also found that starting with a smaller average particle size of sample gave higher overall gasification rates. A rate expression of the Langmuir-Hinshelwood type was then used to satisfy the experimental data at different H2 partial pressures up to carbon conversion of 85-90%. (C) 2004 Elsevier Ltd. All rights reserved.