The aluminates of the trivalent ions of Gd, Eu, and Sm are isostructural with GdFeO 3. They belong to space group YD~-Pbnm with four distorted perovskite units in the true crystallographic cell. The aluminates of the trivalent ions of Nd, Pr and La are rhombohedral belonging to space group D~d--R3m with two formula units in the unit cell. These crystals bear a very close structural relationship to the orthorhombie ones.LaA103 undergoes a transition at 435±25 ° C. to the simple cubic cell containing one formula unit. Evidently, the transition is one of higher than first order. There is no crystallographic transition of PrAI03 below 950 ° C. but a gradual change toward the cubic phase similar to that in LaAl03 is indicated. 1020 CRYSTALLOGRAPHIC STUDIES OF PEROVSKITE-LIKE COMPOUNDS. II