Even though Pourbaix diagrams are useful for a metal corrosion potential estimation they have, however, some important limitations:
# Equilibrium is always assumed, though in practice it may differ.
# The diagram does not provide information on actual corrosion rates.
# Does not apply to alloys.
# Does not indicate whether passivation (in the form of oxides or hydroxides) is protective or not. Diffusion of oxygen ions through thin oxide layers are possible.
# Excludes corrosion by chloride ions (,  etc.).
# Usually applicable only to temperature of , which is assumed by default. The Pourbaix diagrams for higher temperatures exist.