The characteristic effects of the main operating parameters in pressurized fluidized bed gasification, such as pressure and product gas composition, and of inorganic material on peat char gasification reactivity were studied. The measurements were carried out isothermally in a pressurized thermobalance at temperatures between 1023 and 1233 K and pressures up to 1.5 MPa. Steam and carbon dioxide, both pure and mixed with the product gases H2 and CO, were used as reaction agents. The reactivity was expressed in the form of instantaneous gasification rate vs. char burnoff. The steam gasification rate of peat char was only slightly higher than the CO2 gasification rate, and the gasification rates decreased at increasing pressure in both steam and carbon dioxide. The steam gasification rate of the peat char increased to a maximum before decreasing with increasing char burnoff. In carbon dioxide, the main trend was that the gasification rate slightly increased with the burnoff. Demineralization of the peat decreased the reactivity and also removed the negative burnoff behaviour observed in steam gasification. The presence of the product gases H2 and CO inhibited the gasification of the peat char almost entirely.