c‐axis oriented films of YbBa2Cu3O7—y have been prepared by postdeposition annealing of metal (Yb, Ba, Cu) naphthenate gels spin‐coated on SrTiO3 (001) and LaAlO3 (001) substrates in the temperature range from 650 to 900 °C under oxygen partial pressures from about 105 to 10 Pa. High resolution electron microscopy studies showed that the thickness of the as‐prepared c‐axis YbBCO films was in the range from 80 to 100 nm after postdeposition annealing at 725 °C for the film on SrTiO3 and at 750 °C for the film on LaAlO3; above this thickness, a small amount of Yb2O3, CuO, and random‐oriented Yb123 phases were observed. The c‐axis film obtained on the SrTiO3 (001) substrate is defective with stacking faults to form a defect microstructure rather than forming the well‐ordered YbBa2Cu4O8 (Yb124) phase. The film obtained on the LaAlO3 (001) substrate, in contrast to that on SrTiO3, involves a small amount of a‐axis Yb123 grains with dimensions of 5 to 30 nm. The Tc,zero value is 89 K for the film derived on SrTiO3 and 85.5 K for the film on LaAlO3.