SnO 2–NiO and SnO 2–CoO powders mixed in a molar ratio of 92: 8 were reactively sintered for up to 200 h at 1400 °C to form composites having NiO and Co 2SnO 4 particles embedded in Ni- and Co-doped SnO 2 grains, respectively. Analytical electron microscopic observations indicated the embedded particles remained nonepitaxial with respect to the host grains despite prolonged holding at a high homologous temperature, owing to a rather limited solid solubility and vague interfacial energy cusp. Upon cooling or solution annealing at 900 °C, the Niand Co-doped SnO 2 formed {100}, {110}, {101} and/or (001)-specific Guinier–Preston zone plates and dislocations. The formation of additional commensurate superstructure in Ni- but not Co-doped SnO 2 indicated a coupled atom clustering and ordering process for the former during solution annealing.