The phase relations of the system Cr 2O 3TiO 2 were determined at temperatures between 1400 and 1765°C in air. Discrete homologous series of Cr 2Ti n-2 O 2 n-1 , with n = 6, 7, 8, were found to be stable as single phases in the range of certain temperatures, while a continuous solid solution existed in the composition of n > 8 below 1425°C. This presence and its stable region of a new compound of Cr 2TiO 5 corresponding to n = 3 are revealed in the present paper. Cr 2Ti 2O 7, the so-called E phase, existed in wide homogeneity range, corresponding to the composition of approximately 3 < n < 5. High-temperature phases (called n and n' phases in the present work) existed above 1425°C and seemed to be closely related to each other from the viewpoint of the structure except that some X-ray diffraction lines of n phase were strongly diffused. Both rutile and chromia had limited solid solubilities. In the present paper, phase relations between Cr 2O 3 and TiO 2 are summarized in a phase diagram.