When hydrated, it forms plumbic hydroxide or lead(IV) hydroxide, Pb(OH)4; given the formula, this is a mainly hypothetical compound.
Lead dioxide is amphoteric. Lead dioxide can dissolve in strong base to form plumbate ion, Pb(OH)62−. This can then form plumbate compounds. In acid conditions, it is typically reduced to lead(II) ion, Pb2+; lead(IV) ion, Pb4+, is not found in aqueous solution.
The most important use of lead dioxide is as the cathode of lead acid batteries. This arises from the anomalous metallic conductivity of PbO2—TiO2, ZrO2, GeO2, and SnO2 are all insulators with a band gap around 3eV, however PbO2 is a metallic conductor. This is thought to be due to anionic vacancies in the structure creating a formally mixed valent lead oxidation state.
Pb + PbO2 + 2HSO4− + 2H+ → 2PbSO4 + 2H2O, E = +2.05 V