Borates find application in the glass industry, in agriculture, are used as detergents, and in medical as well as in entertainment electronics, and also as nonlinear optical materials. The study of the corresponding compounds however is usually limited to ambient-pressure conditions. In contrast, this study focusses on the synthesis of borates under high-pressure conditions and on the characterization of the resulting compounds. Crystalline borates of monovalent alkali metals and pseudo alkali metals as well as divalent alkaline earth and transition metals were synthesized, wherein the high-pressure conditions were produced with a hydraulic 1000 t press and a modified Walker module. The resulting compounds were characterized using X-ray diffraction experiments and various spectroscopic methods. Ten publications in scientific journals were derived from these studies, representing the core of this cumulative work. The methods used for the synthesis and characterization are described in detail and the specifics of the individual compounds are summarized.