Control of combustion product emissions in both sub- and super-sonic jet engines can be facilitated by measurement of NOx levels with metal oxide sensors. In2O3, metal-doped SnO2, and SnO2 (as well as other materials) show resistivity changes in the presence of NOx but often their sensitivity, stability, and selectivity are low. This study was designed to develop new synthetic pathways to precursors that produce high purity, two phase In2O3-SnO2. The precursors were formed by complexation of tin(IV) with chelating aryloxide ligands to give the ammonium salt, (NH4)(2)[Sn(ligand)(3)]. xH(2)O or the neutral molecule, [Sn(ligand)(2)]. xH(2)O, followed by reaction with In(III) to form the monomolecular precursors. Thermal studies of these precursors were carried out by thermal gravimetry (TG) and differential scanning calorimetry (DSC). Further studies by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) were also conducted.