The application of high pressure kinetic and thermodynamic techniques in mechanistic studies of chemical reactions in solution, can contribute towards the elucidation of the underlying reaction mechanisms. In this review the fundamental principles involved in the construction of reaction volume profiles and the mechanistic interpretation of the latter are presented for various types of reactions in inorganic, organometallic and bioinorganic systems. These include thermal and photo-induced ligand substitution and electron-transfer reactions, as well as processes that involve the activation of small molecules. The mechanistic insight gained through volume profile analysis for non-symmetrical reactions forms the theme of this contribution. (C) 1999 Elsevier Science S.A. All rights reserved.