We report here the influence of growth temperature of CeO2 buffer layer T-(CeO2) as well as the post-annealing of the buffer layer on the crystallinity and the microwave surface resistance R-s of DyBa2Cu3Oz (DBCO) films grown by pulsed laser deposition (PLD). It is found that (i) an increase in the T-(CeO2) facilitates the epitaxial growth of the CeO2 films, which is a prerequisite to obtain the high quality superconducting films and (ii) the post-annealing of buffer layer at 1050 degrees C in flowing O-2 for 1 h leads to a profound improvement in the morphology and in the crystallinity of CeO2 films. Apparently, there exists a critical growth temperature (T-(CeO2) = 800-820 degrees C, as found in this and previous study [J.C. Nie, H. Yamasaki, Y. Nakagawa, K.D. Bagarinao, M. Murugesan, H. Obara, Y. Mawatari, J. Crystal Growth 284 (2005) 417]) for CeO2, below which the crystalline quality of CeO2 films might not be improved merely by the post-annealing. It is explained that for T-(CeO2) < 800 degrees C, the as-grown CeO2 grains are longitudinal in shape, and it forms corrugated structure upon annealing. This poor morphology yields a. deteriorated crystallinity (i.e., a large value of Delta omega and Delta phi, and the formation of secondary phase) for the CeO2 as well as the overlying DBCO films, and hence a poor microwave performance of DBCO films for T-(CeO2) < 800 degrees C. We also observed that the R-s in DBCO films monotonously decreased with increase in the growth temperature of CeO2. Further, the post-annealing of the CeO2 buffer layer prior to DBCO deposition greatly helps to reduce the R-s at the liquid N-2 temperature region, which is immensely required for the use of superconducting films in the passive microwave device components. Thus, the 800-820 degrees C of T-(CeO2) and the post-annealing of CeO2 at 1050 degrees C in flowing O-2 for 1 h may be readily exploited to grow RBCO (R = Y or rare-earth elements) films for microwave applications on the technologically viable r-Al2O3 substrates. (C) 2007 Elsevier B.V. All rights reserved.