Synthesis and characterization of Ba2LaNbO6which is a new substrate material for YBa2Cu3O7−&dgr;superconductor are reported. Ba2LaNbO6has a complex cubic perovskite structure (A2BB′O6) with a lattice constanta=8.60 A˚. No detectable chemical reaction between YBa2Cu3O7−&dgr;and Ba2LaNbO6was observed even under severe heat treatment. The dielectric constant and loss factor of Ba2LaNbO6are in a range suitable for its use as a substrate for microwave applications. Superconducting YBa2Cu3O7−&dgr;–Ag thin films are growninsituon polycrystalline Ba2LaNbO6by pulsed laser ablation method. The film exhibited (00l) orientation of an orthorhombic YBa2Cu3O7−&dgr;phase. The films gave aTconset of 91 K andTc(0)of 89 K. ©1996 American Institute of Physics.