The present work considers the reaction kinetics between titanium dioxide, TiO2 (rutile) single crystal and a thin layer of indium oxide. In2O3 deposited on its surface. The reported experimental data are reflective of the chemical reaction involving the diffusive transport of In3+ in the rutile phase. The reaction progress at 1173 K is monitored using the secondary ion mass spectrometry (SIMS) technique. It is shown that the SIMS depth profiles may be considered in terms of two distinctly different components, related to the surface layer of In2O3, and the rutile single crystal phase beneath. The depth profile of the rutile phase involves the region related to bulk diffusion of indium as well as the background composition. The bulk diffusion coefficient of indium, In3+ in single crystal TiO2 (rutile) at 1173 K and p(O-2) = 21 kPa was determined to be 4.4(+/-0.2) x 10(-18) m(2) s(-1). (C) 2011 Elsevier B.V. All rights reserved.