Publisher Summary This chapter provides an overview on the tribochemistry concept. The term “tribochemistry” originated from two words “tribo” and “chemistry” of reactions occurring between the lubricant and the surfaces. It relates directly to the combinations of all sciences and technologies associated with the chemical reactions in mineral and synthetic oil formulations and with tribofilm formation on metal surfaces under boundary lubrication. The basic processes of dissolution, acid-base interaction, micellization, solubilization, oxidation, and reduction take place in oil formulation. During engine operation, additives of the lubricant interact continuously with engine surfaces and themselves. Surfactant additives are fundamental to reverse micelles (RMs) formation in oil formulation. The formation of RMs, because of dipole–dipole interactions between the polar heads of the surfactant molecules, may play an important role in oil formulation. In the tribosystem, the flow of energy is accompanied by an increase in entropy of the total system and is reflected by the tribochemical reactions and deterioration of lubricant quality.