The influence of temperature, mass transfer, and applied potential on the dissolution of aluminum and aluminum alloys 3003 and 6063 in concentrated phosphoric acid is probed by steady-state and transient electrochemical methods. Resulting surface morphologies are characterized with optical microscopy. The alloys and pure aluminum exhibit a similar electrochemical behavior and surface finish. The surface varies from matte at low temperatures to polished at high temperatures, with a transition near 65 degrees C. The impedance, polarization, and Arrhenius behavior of the system is compared to that found for iron and copper dissolution in concentrated phosphoric acid.