Ionization potential indicates a substance's tendency to loose electron and become a positive ion. So, a substance becomes ion more easily if it has a lower ionization potential (lower energy needed to make it an ion).
Oxidation potential indicates a substance's tendency to loose electron (oxidize) and become a positive ion. So, a substance should become oxidized more easily if it has a lower Oxidation potential. But it is NOT the case. A substance becomes oxidizied more easily if it has a higher oxidization potential.
Why is it so? Can anyone explain? And again, Potassium becomes ionized more easily than Lithium according to the reactivity series for metals, but Lithium becomes oxidized more easily than Potassium according to Electrochemical series. Why?