Thin superconducting films of YBa 2 Cu 3 O 7 - y (Y123) and YbBa 2 Cu 3 O 7 - y (Yb123) have been derived from metal naphthenates gels spin-coated on SrTiO 3 (001) 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 SrTiO 3 (001) substrate. High-resolution electron microscopy further reveals that the c-axis Y123 thin film was epitaxially formed, covering the substrate surface. The 90 o oriented a- and c-axis Y123 components are found to form meandering grain boundaries.