Single crystals of CaGdAlO4 that have not been used previously as a substrate material for HTSC films were grown by Czochralski method and applied for the deposition of the Bi2Sr2CaCu2O8−x and LuBa2Cu3O7−z thin films. The main advantages of the CaGdAlO4 crystals are sufficiently low dielectric constant, appropriate crystal lattice match with most HTSC, fairly high crystal perfection and reproducibility of the growth process. Bi2Sr2CaCu2O8−x films were prepared by “off-axis” DC magnetron sputtering and LuBa2Cu3O7−z films were obtained by flash evaporation MOCVD technique on the (001) oriented CaGdAlO4 substrates.