Thermal fluctuations in the electric conductivity of YBa 2 Cu 3 O 7−δ superconducting thin films grown on Sr 2 YSbO 6 novel substrate materials in the film form were experimentally studied. YBa 2 Cu 3 O 7−δ films were grown by using a dc-technique on Sr 2 YSbO 6 substrates, which were produced by rf magnetron sputtering. X-ray diffraction analysis evidenced that the Sr 2 YSbO 6 films grow on conventional SrTiO 3 substrates in a preferential orientation along the (100) planes direction with lattice parameter a=4,43(2)Å. The YBa 2 Cu 3 O 7−δ thin films, grown on Sr 2 YSbO 6 films, exhibit an oriented growth in the (001) crystallographic direction, with lattice constant c=11,65(9)Å. Morphological characterizations were performed by means atomic force microscopy. Experiments of electrical resistivity show that the YBa 2 Cu 3 O 7−δ films present a normal-superconducting transition with critical temperature T c =82,33 K. Fluctuation analysis for the YBa 2 Cu 3 O 7−δ thin films were performed by utilizing the concept of logarithmic derivative of the conductivity excess. Above the critical temperature T c we experimentally determine the occurrence of Gaussian 3D, 2D and fractal fluctuation regimes. A genuinely critical region identified by the exponent λ CR =0,35 were obtained close to T c . This critical regime is effectively described by the 3D-XY model.