A low voltage argon ion sputter technique was used to form grain boundary junctions in YBa2Cu3O7−xthin films on MgO. The YBa2Cu3O7−xthin film grown on a pre‐sputtered region of MgO was rotated 45° about the [001] axis relative to the YBa2Cu3O7−xthin film grown on an adjacent unsputtered region of the substrate. YBa2Cu3O7−xthin films were grown using pulsed organometallic beam epitaxy (POMBE). The current‐voltage and resistance‐temperature characteristics of individual grain boundary junctions demonstrated weak‐link‐type behavior. Sputter‐induced 45° grain boundary junctions are advantageous in device applications because they are planar and simple to form in many configurations. ©1995 American Institute of Physics.