Catalytic decomposition of hydrazine monohydrate (N2H4 center dot H2O) represents a promising hydrogen storage/production technology. Nowadays, the development of N2H4 decomposition catalysts is sluggish due primarily to a lack of universal screening rules. Herein, with the aid of first-principles calculations, we identify a reliable descriptor, N2H4 adsorption energy, to properly address N2H4 decomposition kinetics on TM catalysts. Particularly, we extract linear scaling relations between the adsorption energetics of key intermediates, H (and N2H3) vs. NH2 that exert a fundamental limitation on the H-2 selectivity of N2H4 decomposition over elementary transition metal catalysts. We propose that catalysts with optimum H-2 selectivity may be achieved by independently stabilizing and destabilizing adsorption of H (or N2H3, or both) and NH2, respectively. The disclosed dissociation behaviors of N2H4 and their physical origins are expected to advance the rational design of advanced catalysts for selectively promoting H-2 production from N2H4. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.