Abstract: The physical features of nanosized combined support and CoMo supported catalysts with different nanosized scales were summarized. NH3-TPD was used to determine the acidic features of nanosized TiO2/Al2O3 composites and CoMo supported catalysts. The results showed that the supported nanosized TiO2 and the matrix γ-Al2O3 interacted with each other. When a small quantity of TiO2 was carried on the matrix, the total amount of acid sites increased with TiO2 content, and the composites had larger acid amount than matrix. The CoMo catalysts had much larger acid amount. From the shape of the TPD traces of the composites, we reached the conclusion that nanosized TiO2 is prior to support on the strong acid sites of the matrix. The crystalline size of TiO2 had more influence on acid amount than on acid distribution. The novel CoMo supported catalysts possesse suitable aperture properties and high hydrogenation activity for oil refining.