The first phase is known as the oxidation phase or the oxidative phase. In this phase, what we basically do is we essentially oxidize glucose molecules. More specifically, we oxidized glucose phosphate molecules into ribose five phosphate molecules. In the process we also generate those that reducing agent, the NADPH molecules. So this is the reaction that takes place in the oxidative phase. So we have glucose six phosphate we have two NADP plus molecules and an H two O molecule.