Heterogeneous catalysts are materials with a complex structure at the atomic to mesoscopic scale, which depends on a variety of empirical parameters applied during preparation and processing. Although model systems clarified the general physical and chemical phenomena relevant to catalysis, such as hydrogen spillover, a rational design of heterogeneous catalysts is impeded by the sheer number of parameters. Combinatorial methods and high-throughput techniques have the potential of accelerating the development of optimal catalysts. We describe here a combinatorial approach based on hydrogen adsorption/absorption and hydrogen-deuterium exchange quantified by neutron imaging. The method coined CONI is capable of measuring more than 50 samples simultaneously. As a proof of concept, we study Pt catalyzed WO3 as an archetypal spillover system, and a Ni-catalyst supported on Al2O3 and SiO2. CONI is ideally suited to distinguish between irreversible surface adsorption and reversible bulk absorption, providing quantitative information. Concretely, CONI yields the number of reversibly adsorbed/absorbed hydrogen atoms in and on a great number of various catalysts in a single experiment.