Microchannel reactors appear attractive as integral parts of fuel processors to generate hydrogen (H-2) for portable and distributed fuel cell applications. The work described in this paper evaluates, characterizes, and demonstrates miniaturized H-2 production in a stand-alone ammonia-fuelled microchannel reformer. The performance of the microchannel reformer is investigated as a function of reaction temperature (450-700 degrees C) and gas-hourly-space-velocity (6520-32,600 Nml g(cat)(-1) h(-1)). The reformer operated in a daily start-up and shut-down (DSS)-like mode for a total 750 h comprising of 125 cycles, all to mimic frequent intermittent operation envisaged for fuel cell systems. The reformer exhibited remarkable operation demonstrating 98.7% NH3 conversion at 32,600 Nml g(cat)(-1) h(-1) and 700 degrees C to generate an estimated fuel cell power output of 5.7 W-e and power density of 16 kW(e) L-1 (based on effective reactor volume). At the same time, reformer operation yielded low pressure drop (<10 Pa mm(-1)) for all conditions considered. Overall, the microchannel reformer performed sufficiently exceptional to warrant serious consideration in supplying H-2 to fuel cell systems. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.