[en] Superconducting thin films of Bi-Ca-Sr-Cu oxide, with T/sub c/ onset of approximately 90K, have been prepared by rf magnetron sputtering on sapphire with and without a CaZrO/sub 3/ buffer layer, ZrO/sub 2/-coated silicon (111), as well as on single crystal MgO (100). Sintered pellets of Bi/sub 2/CaSr/sub 2/Cu/sub 2/O/sub 8+x/ (2122) and Bi/sub 4/Ca/sub 3/Sr/sub 3/Cu/sub 4/O/sub 16+x/ (4334) were employed as targets. The as-deposited films were amorphous insulators which were then annealed in various ways. Zero resistance at 72K for films on (100) MgO was achieved after annealing in air at 810⁰C for 2 hr. However, the X-ray diffraction pattern showed that two superconducting phases, i.e. Bi/sub 2/CaSr/sub 2/Cu/sub 2/O/sub 8+x/ (2122) and Bi/sub 2/Ca/sub x/Sr/sub 2-x/CuO/sub 6+y/ (2021), are present, and that films have preferred orientation with c-axis normal to the substrates