Traditional hydrometallurgical approaches for the metals recovery use the different leaching agents: halides, cyanide, thiocyanate, thiourea, thiosulfate, polythionates, and leaching microorganisms. Polythionates are very effective but their industrial application showed some problems / limitations. The monograph describes formation of polythionates of organic bases: they are in more effective for leaching and have no limitations of inorganic polythionates. The monograph presents the new general theory of the organic base polythionates formation. The new theory explains all experimental data published in the affiliated chemical and hydrometallurgical literature. In whole, the monograph is intended for chemists and microbiologists working in the field of hydrometallurgy.