The monograph deals with phase formation in sulfate-fluoride aqueous systems of group IV element compounds, including demarcation of the areas of their existence and establishing their chemical composition and refractometric, roentgenometric, thermal, and IR-spectroscopic characteristics. For a number of compounds their structure with elementary cell parameters as well as types of chemical bonds have been determined. All the currently known compounds (approximately 400 compounds belonging to 9 groups with 37 series) are compared with one another, which allowed to systematize and predict new compounds (about 30) corresponding to fluoro-, sulfate-, and fluorosulfate metallates of group IV elements with dissimilar outer-sphere cations. Some of these compounds are unique and may find wide application. The monograph consists of 8 chapters in which 21 physico-chemical systems and 8 sections are examined explaining formation of compounds, including their comparative characteristics. The book is intended for researchers, engineers, higher-education teachers, post-graduate and students.