The monograph is devoted to the consideration of physico-chemical problems of energy transformation in biomembranes during respiration and photosynthesis. Presented modern ideas about the organization of electron transport chains of mitochondria, chloroplasts and chromatophores . Particular attention is paid to the comparison of electron transport complexes of different groups of organisms. Kinetic and thermodynamic features of electron transfer in multienzyme complexes are analyzed. The kinetics of electron transfer in photosynthetic reaction centers of phototrophic bacteria and green plants is considered The book is of interest to biophysicists, biochemists, as well as chemists and physicists studying the problems of bioenergy and biokinetics.