A solvothermal reaction can be described as a chemical reaction involving a solvent either in subcritical or supercritical conditions between different precursors. Such a solvent can act as a chemical component or a fluid phase able, through its physico-chemical properties, to induce the synthesis reactions. During the last fifteen years, solvothermal reactions have been used in different scientific areas involving basic or applied research. Several domains have been developed in Materials Chemistry: (i) the synthesis of novel materials, (ii) the development of new low temperature processes able to prepare functional materials, and in Materials Science: (i) new crystal growth processes, (ii) thin film deposition and (iii) sintering processes at low temperature. In Materials Chemistry three illustrations are described: (i) the synthesis through “geomimetism” of a new family of layered oxides: the phyllosiloxides, (ii) the synthesis of inorganic-organic materials, (iii) the potential of solvothermal processes for producing c-BN.