The production of ATP with the help of energy liberated during oxidation of reduced coenzymes and terminal oxidation is called oxidative phosphorylation. Peter Mitchell (1961) put forward a hypothesis known as chemiosmotic hypothesis for ATP synthesis. According to this when electrons flow from dual proton, electron carrier to a non-hydrogen carrier the H+are released and expelled into the intermembrane space and thus, creates a proton gradient with higher concentration of H+in the inter membranous space than the matrix. Due to proton motive force the protons flow back and energy liberated during this back flow of protons activate ATPase present in F1 head to synthesize ATP.