Nickel (Ni) catalysts supported on cerium-lanthanum oxide were prepared by two different preparation techniques and have been tested in the temperature range of 500-750 degrees C for selective catalytic oxidation of ammonia to nitrogen in gasified biomass. The two different catalyst preparation methods used are the conventional and the microemulsion (water-in-oil). The effect on catalytic activity of different Ni loadings was also tested in combination with the preparation method. Catalyst characterisation was focused on BET and XRD analysis. Cordierite monoliths were used in a tubular quartz reactor for the purpose of the activity tests. For simulating the gasified biomass fuel, 400 ppm NH3 was added to the fuel. Water was also present during the activity tests, which were carried out at fuel rich conditions. Results showed that the microemulsion-prepared catalysts obtained higher performance than the conventional ones, with the best catalyst reaching 98% ammonia conversion and 99% nitrogen selectivity at 750 degrees C. The more the Ni supported on the catalyst, the higher the catalytic activity. Constant conversion and negligible carbon deposition were two other important characteristics for the microemulsion-prepared catalysts. (c) 2005 Elsevier B.V. All rights reserved.