Aiming to investigate the possibility Of exploitation of perennial crops for energetic uses, five sustainable energy plants, previously devolatilized, were gasified by carbon dioxide up to 950 degrees C in a thermobalance system, coupled with a quadrupole mass spectrometer. The gasification reactivity, thermal decomposition characteristics, and products of gasification were determined, and the effect of inherent inorganic matter of these fuels on process parameters was examined. The bulk of the gasification process occurred above 800 degrees C, with main products CO and lesser amounts of H-2 and H2O. Gasification reactivity was highly correlated to the specific surface area of the chars. Inherent mineral species K, P, S, and Cl influenced the temperature sensitivity of the process and reduced the gasification rate and H-2 production. However, a lower pyrolysis temperature of char generation increased the gasification reactivity and greatly enhanced H-2 production.