The charge of the cerium ion depends on its oxidation state. Cerium can exhibit multiple oxidation states, including +3, +4, and sometimes even +2.

- The most common oxidation state for cerium is +3, and the corresponding ion is called the cerium(III) ion (Ce³⁺).

- In this state, cerium loses three electrons from its outermost shell, resulting in a positive charge of 3.

- Cerium can also form the cerium(IV) ion (Ce⁴⁺) by losing all four of its valence electrons.

- The cerium(IV) ion has a charge of 4+ and is a strong oxidizing agent.

- Less commonly, cerium can also exist in the +2 oxidation state, forming the cerium(II) ion (Ce²⁺) by losing two electrons.

The charge of the cerium ion in a specific compound or reaction will depend on the specific chemical context and oxidation-reduction conditions.