What two molecules pass high energy electrons to the electron transport chain?

The two molecules that pass high-energy electrons to the electron transport chain are NADH and FADH2. These molecules are generated during metabolic processes such as glycolysis and the Krebs cycle. NADH donates electrons to Complex I, while FADH2 donates electrons to Complex II of the electron transport chain, ultimately contributing to the production of ATP through oxidative phosphorylation.