Abstract Single crystals of CdGeO3 ilmenite have been synthesized at p = 10.3 GPa and T = 1200°C. The crystal structure of CdGeO3 ilmenite has been determined with 781 counter-measured intensities and refined by the least-squares method to R = 0.048. CdGeO3 ilmenite is trigonal with a = 5.0988(4) Å, c = 14.932(3) Å; R[unk] and Z = 6. Cd2+ and Ge4+ ions occupy alternate basal-plane layers of cationic sites, and there is no observed disordering of Cd2+ and Ge4+ ions. The mean distances of Cd – O and Ge – O are 2.321 Å and 1.921 Å, respectively, in good agreement with those expected from the effective ionic radius of Cd and Ge in six-fold coordination. The height of the CdO6 octahedra along the c axis is about 30% greater than that of GeOe octahedron. Crystal-chemical analysis of the ilmenite-type compounds suggests that c is chiefly affected by the size of divalent cations in the ilmenite structure, while a is dominantly controlled by the size of the tetravalent cation. CdGeO3 ilmenite has the largest value of c/a among compounds with the ilmenite structure, as a result of its largest difference in ionic radius between paired cations.