Surface acoustic wave (SAW) velocity and attenuation measurements have been performed on high-temperature superconductingYBa2Cu3O7−&dgr;(YBCO) thin films (deposited on nonpiezoelectric substrates), and YBCO single crystals. A “bridge” technique is employed in which piezoelectric substrates, patterned with interdigital transducers, are bonded to the sample under investigation. The temperature dependence of 168 MHz SAW attenuation in a single crystal near its superconducting transition has been measured in applied magnetic fields up to 1.6 T. Features are seen above the superconducting transition temperature which may be indicative of a transition in the electric polarization of the material. A field-dependent attenuation peak, seen in the superconducting state, is discussed in terms of the theory of thermally activated vortex motion. ©1997 American Institute of Physics.