We present here the testing results in NH3 decomposition of a catalytic structured reactor consisting of a cordierite monolith coated with a catalyst layer of well-dispersed Ni on mesoporous gamma-alumina. The catalyst is low cost, stable and exhibits high activity, achieving complete conversion of pure NH3 at a temperature as low as 873 K. Notably, the conversion is significantly higher when the catalyst is in the form of monolith than in a packed bed of the same catalyst in the form of particles smaller than 200 mu m, achieving total NH3 conversion at 100 K lower temperature. These results along with the process intensification derived from the use of monolithic catalyst make this catalyst a promising candidate for in situ H-2 generation from ammonia to feed fuel cells in vehicles or industry. (C) 2010 Elsevier Inc. All rights reserved.