Li(s) + NaOH(aq) → LiOH(aq) + Na(s)

The oxidation state of Li changes from 0 to +1.

Initially, Li(s) has an oxidation state of 0. When Li reacts with NaOH, it loses one electron to oxygen in the hydroxide ion (OH-), resulting in the formation of LiOH where Li has an oxidation state of +1.