Thin superconducting films of YBa2Cu3O7-y (Y123) and YbBa2Cu3O7-y (Yb123) have been derived from metal naphthenates gels spin-coated on SrTiO3 (0 0 1) substrates. X-ray diffraction and transmission electron microscopy (TEM) show that the Yb123 film with its c-axis perpendicular to the substrate surface was epitaxially grown; while a mixture of c-and a-axis Y123 was derived on the SrTiO3 (0 0 1) substrate. High-resolution electron microscopy further reveals that the c-axis Y123 thin film was epitaxially formed, covering the substrate surface. The 90 degrees oriented a- and c-axis Y123 components are found to form meandering grain boundaries.