The concept of the decisive role of solid catalysts in the reaction of low-temperature decomposition of H2S is considered in the framework of non-equilibrium thermodynamics of an irreversible process in an open system . The reaction proceeds at room temperature without the use of external energy sources due to the internal chemical energy of H2S molecules. In the gas phase, this reaction is thermodynamically impossible. The reaction products, along with hydrogen, are either solid sulfur (sulfide catalysts) or diatomic gaseous sulfur in the ground triplet state (metal catalysts) . Various types of solid catalysts have been proposed for the process . The developed concept makes it possible to solve not only the problem of the effective practical use of H2S, but also opens new pages in the chemistry of this substance as a source of atomic hydrogen and an energy supplier for the activation of chemically inert molecules (CO2, N2, Ar, etc). Moreover, the gaseous triplet sulfur discovered by us can be used in various fields of chemistry, pharmacology, medicine, etc. Thus, "useless" H2S acquires the status of a "useful" chemical, which will undoubtedly be in demand to solve problems that could not be realized within the framework of the previous paradigm of high-energy utilization of H2S .