Strictly speaking, oxidation is a reversible process.

Can oxidation reduction reactions be reversed?

Yes, redox reactions are typically reversible. ... For example, a redox reaction run in an electrochemical cell can be reversed with the help of an electrolytic cell featuring the same reactants.

Can oxygen be oxidized or reduced?

Oxidation and reduction in terms of oxygen transfer

Oxidation is the gain of oxygen. Reduction is the loss of oxygen.