Seven different commercial nickel-based catalysts for steam reforming of light hydrocarbons and of heavier hydrocarbons were tested for tar removal in a flue gas from an atmospheric fluidized bed biomass gasifier, using air as the gasifying agent. The catalysts were provided by BASF AG, ICI-Katalco, Haldor Topsoe a/s, and United Catalyst Inc. The facility used is a small pilot plant, and the catalytic reactor operates in full flow with a real gasification gas. A guard bed with a calcined dolomite is used to decrease the tar content at the inlet of the catalytic bed to a level below 2 g/m(n)(3). The variables studied include the temperature (730-850 degrees C) of the catalytic bed, gas residence time, steam content in the flue gas, and composition of the reacting atmosphere. All catalysts for steam reforming of naphthas provide a similar and very high activity. Values of the apparent activation energy and preexponential factor are given and analyzed for the most active catalysts. The catalyst life is also studied. No deactivation is observed with times-on-stream of up to 65 h.