Based on the virtual crystal approximation (or Vegard's law), the bond lengths of Ti1-chiSnchiO2 were deduced from those of TiO2 and SnO2, to allow the oxygen position and octahedral distortion to be determined as a function of chi. The oxygen positional parameter (u) increased linearly when the Sn4+ cation (which has a larger ionic radius) was substituted for the Ti4+ cation, whereas the octahedral distortion exhibited a nonlinear decay with increasing chi in Ti1-chiSnchiO2. At the same time, the bond-valence parameter, which relates bond valence to bond length, so that the central atom in the octahedron can retain a constant valence of + 4.0, exhibited a correlation with u for Ti1-chiSnchiO2. The present results indicate that the different phonon/physical properties of TiO2 and SnO2 and/or their dependence on chi in Ti1-chiSnchiO2 can be associated with different octahedral distortions.