The goal of this study is to assess the release of contaminants during the oxygen/steam gasification of two waste-derived fuels using three different bed materials. The solid recovered fuels (SRFs) were tested at 850 degrees C in a bench-scale fluidized-bed reactor with sand, dolomite, and olivine as bed materials. The effects of the experimental conditions were assessed based on the gasification performance (product yields, carbon conversion, etc.) and the presence of tar, including polycyclic aromatic hydrocarbons (PAHs) and minor contaminants (HCl, H2S, HCN, and NH3) in the producer gas. The results show higher gas yields with the use of catalysts, particularly dolomite, and a lower catalytic activity of olivine toward tar abatement. The presence of contaminant precursors (Cl, S, and N) together with the concentration of metals from both catalysts and waste fuel ashes appear to influence the evolution of contaminants: In general; dolomite is more efficient than olivine in reducing tar compounds and most minor contaminants but NH3, whereas olivine mainly exhibits the ability to reduce light PAHs and nitrogenous compounds (HCN and NH3) in the producer gas.