The postperovskite structure (pPv) is a high-pressure form of a highly distorted perovskite phase. In contrast to the Pv structure, the pPv structure consists of layers of corner and edge-shared octahedra that stack along the b axis of the orthorhombic unit cell. CaRhO3 (Rh4+; t2g5) has been recently synthesized in our laboratory with either the pPv (prepared at 6 GPa) or the Pv structure. The magnetization of the pPv phase suggests a canted spin structure below TN (~90 K). Unfortunately, the spin structure of any pPv oxide has been resolved by neutron diffraction. Since pPv CaRhO3 is an insulator, localized electrons on Rh4+ makes it a Jahn-Teller active ion, suggesting a large octahedral distortion, which would drive the canted spin structure by the single-ion anisotropy. In order to confirm this scenario, we have to independently resolve the local structural distortion and the spin structure. Neutron diffraction is an invaluable tool for this task. We ask for 2 days of beamtime at D2B and 1 day at D20, to investigate the evolution of the crystal (also for the Pv phase) and magnetic structures.