A study of the steam gasification of Cynara cardunculus L. was carried out in order to characterise the gas phase with a view to its energy use, analysing the influence of water partial pressure, particle size, and temperature. The main gases generated were H-2, CH4, CO, and CO2, with a higher heating value between 10 and 11 MJ/N m(3). The gas in greatest proportion was H-2; that in the smallest proportion was methane, which was pyrolytic in origin. Within the range of variables studied., the particle size had no significant effect on the process. Temperature and water partial pressure exerted positive effects on the main parameters of the process, increasing the reaction rate, the gas yield and production, the conversion and the energy generated per kilogram of initial residue (Cynara). The experimental results show that the water-gas shift reaction is the main determinant of the composition of the gases. For this reaction. an increase in temperature leads to a greater formation of CO, and an increase in water partial pressure to a greater formation of CO2. The energy yield of the gasification process presented values between 0.5 and 0.85. Temperature and water partial pressure had a positive effect on this parameter. (C) 2002 Elsevier Science B.V. All rights reserved.