The book describes the results of investigations of the electrophysical, chemical, gas-dynamic and other processes in low-temperature plasma, their diagnostics, modelling and application in various areas of science and technology. Special attention is given to the problems associated with physico-chemical processes and chemical reactions in nonequilibrium and (quasi) equilibrium low-temperature plasma. Kinetic and thermodynamic aspects of plasmochemical reactions and their mechanisms, determined mainly by reactions under electron impacts and reactions of vibrationally excited molecules, are discussed.