The development of a base metal catalyst which shows high performance for the ammonia (NH3) decomposition have been conducted. For the Ni and Co based catalysts using alpha-Al2O3 as a support, the performance of the single metal catalysts was lower than that of the gamma-Al2O3 supported catalysts. However, its performance was greatly improved by using a binary metal catalyst system. Based on the XRD analysis, it was found that Ni and Co supported on alpha-Al2O3 were alloyed. TEM observation confirmed that the metal particle size in the alpha-Al2O3 supported Ni-Co catalyst is smaller than that of the single metal catalysts (Ni/alpha-Al2O3 or Co/alpha-Al2O3). Furthermore, in-situ XRD and H-2-TPR measurements revealed that the Ni-Co alloy forms during the reduction process. The optimum mixing ratio of Ni and Co components was 1:1, and the optimum pre-reduction temperature before the performance test was 600 degrees C. Studies on the differences of support oxides proved that the improvement effect by alloying can be similarly obtained with the SiO2 supported catalyst, indicating that the catalyst using the support with less interaction between the active metal and the support is more likely to obtain the performance improvement effect by alloying.