The interface between laser deposited Y‐Ba‐Cu‐O thin films and yttria‐stabilized cubic zirconia substrates was studied using high‐resolution transmission electron microscopy andinsituresistivity measurements. It was found that a ∼5 nm layer of low resistivity compound was formed at the interface, at a substrate temperature of ∼650 °C. This result is qualitatively different from other substrates such as SrTiO3and MgO, where the interface compounds are high resistivity oxides. ThisinsituY‐Ba‐Cu‐O thin film is superconducting with aTcof 88 K and aJcof 2×106A/cm2at 77 K.