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Hydrogen is a promising renewable energy source. However, its implementation in industrial processes is challenging since it penetrates metals, resulting in embrittlement, leakage, and a risk of explosion. We explore the combined effect of loading a polymer liner (protecting the metal) with graphene and unsaturated organic molecules on reducing hydrogen diffusion. The suggested combined approach includes (1) the formation of a hydrogen barrier and (2) the chemical absorption of hydrogen. In (1), graphene nanoplatelets (GNPs, impermeable to hydrogen) decrease hydrogen diffusion by one order of magnitude, where small-sized GNPs are found to be more effective than large ones. In (2), the presence of unsaturated organic molecules (getter) not only leads to an efficient chemical absorption of hydrogen (>86% reaction) but decreases its diffusion by two orders of magnitude. The kinetic analysis of a hybrid system (loaded with both the GNP and getter) reveals that the presence of GNPs allows hydrogen to reach distant locations of unsaturated molecules by migrating over the GNP surface (termed spillover). A polymer loaded with unsaturated organic molecules changes its color upon exposure to hydrogen and could serve as a standalone visual hydrogen sensor. These findings provide general guiding principles for designing functional materials for hydrogen detection and its safe transportation and storage. [ABSTRACT FROM AUTHOR]