Abstract: The effect of high temperature treatment on the surface morphology,the phase structure of CeO_2 buffer layers grown on sapphire substrates was studied, and also the growth of CeO_2 on Tl-2212 films. The measurements of AFM and XRD showed that annealing of the CeO_2 films produced drastic change in surface morphology and crystalline quality. Annealing treatment at 950 ℃ for 1 h resulted in atomically flat CeO_2 surface and significant improvement of the crystalline quality of CeO_2 films. Experimental results revealed that the superconductivity of Tl-2212 films is closely interconnected with the crystal quality and morphology of buffer layers. The crack-free films with the thickness of 500 nm grown on such buffer layers had a high transition temperature (T_c =107 K), a high critical current density (J_c=3.9 MA/cm~2 at 77 K and zero applied magnetic field) and a low surface resistance (R_s=281 μΩ at 10 GHz and 77 K).