Oxygen storage materials (OSMs) composed of transition metals are promising in the field of environment protection and energy conversion. In this study, we synthesized LaNi1–xAlxO3 (0 ≤ x ≤ 1.0) solid solutions with a rhombohedral perovskite structure and investigated the effect of Al substitution on their structural stability and oxygen release rate. X-ray diffraction measurements and thermogravimetric analysis revealed that Ni-containing LaNi1–xAlxO3 released/stored oxygen atoms topotactically and reversibly via the Ni3+ ↔ Ni2+ redox reaction. LaNiO3 decomposed into La2O3 and Ni0 at 470 °C in a reducing atmosphere (H2). However, Al-substituted LaNi1–xAlxO3 maintained their perovskite structure even at high temperatures (>800 °C for 0.6 ≤ x ≤ 1.0). The high structural stability of these compounds can be attributed to the suppression of oxygen vacancy ordering. Furthermore, LaNi0.2Al0.8O3 (x = 0.8) exhibited higher oxygen release rate (9.35 × 10–3 mol-O mol-Ni–1 s–1) than LaNiO3 (x = 0; 2.59 × 10–3 mol-O ...