Oxide superconductors in the Y-Ba-Cu-O and Bi(Pb)-Sr-Ca-Cu-O systems with T_c degrees of 93.6 K and 115 K, respectively, have been prepared by the co-precipitation process via the oxine route using nitrates as the starting materials. Chemical homogeneity, stoichiometry and fine particles of the precursor obtained by this process permit a relatively short time for the production of Y- and Bi-based superconducting compounds compared with that obtained by the conventional solid state reaction method. The resulting densities of the sintered samples were typically greater than 90%. X-ray diffraction analysis, energy dispersive spectral analysis and scanning electron microstructural analysis are also reported in this study.