A large resistive transition between 160-200 K has been observed in Y 5Ba6Cu11Ox thin films. The films were deposited on MgO substrates by electron-beam evaporation and annealed through rapid thermal annealing. With 960-980°C, 30-60 s RTA, the films showed a resistance drop about one order of magnitude around 160-200 K. This resistive transition was measured reproducibly over many samples. The preparations and measurements of the Y5Ba6Cu 11Ox films were similar to those of the YBa 2Cu3O7-x films. The x-ray diffraction pattern indicated that the films mainly contain the YBa2Cu3O 7-x phase. The films were polycrystalline with grain sizes of a few μm and an average thickness of 0.4 μm.