Doctor of chemistry, honored science worker of the Russian Soviet Federative Socialist Republic, Professor Roman Victorovich Mertslin was an outstanding scientist, an eminent public figure, Rector of Perm and Saratov universities, a talented teacher, and an organizer of science. R.V. Mertslin’s interests were in the field of theoretical and experimental research of heterogeneous condensed states in multicomponent systems. His works, being of great importance for the development of a theory of phase equilibrium, are well-known to numerous domestic and foreign scientists.