The reaction sintering of TixAly-Al2O3 composites from TiO2/Al starting powder mixtures has been characterized by thermogravimetry and differential thermal analysis (TG/DTA), in situ temperature measurements, and predictions via a continuum model. In order to model the TiO2/Al reaction system, it was necessary to first determine the postmill reactant concentrations and the dominant reaction. The postmill reactant concentrations were obtained from TG/DTA measurements in air, while X-ray diffraction (XRD) was used to gain insight into the reaction mechanisms. A continuum model of the process was fitted to in situ temperature measurements by adjusting two parameters. The model was then used to investigate the effects of various processing conditions on the reaction behavior.