AlP crystals are dark grey to dark yellow in color and have a zincblende crystal structure with a lattice constant of 5.4510 Å at 300 K. They are thermodynamically stable up to 1,000 °C (1,830 °F).
Aluminium phosphide reacts with water or acids to release phosphine:Aluminium phosphide (AlP) is an inorganic compound used as a wide band gap semiconductor and a fumigant. This colourless solid is generally sold as a grey-green-yellow powder due to the presence of impurities arising from hydrolysis and oxidation.
AlP + 3 H2O → Al(OH)3 + PH3 AlP + 3 H+ → Al3+ + PH3