Cobalt can exhibit multiple valencies, with the most common being +2 and +3. The +2 oxidation state (Co²⁺) is more prevalent and stable in many compounds, while the +3 oxidation state (Co³⁺) is less common and typically found in specific complexes and reactions.
In addition to these, cobalt can also appear in other less common oxidation states such as +1 and +4, but these are not as frequently encountered.