A capacitively coupled interdigital probe technique is described whereby the electrical characteristics of thin films at arbitrary frequencies in the range from about 100 kHz to beyond 1 GHz may be studied. Patterning of the film, deposition of electrodes, and bonding of electrical leads are unnecessary, so that all measurements are nondestructive and noninvasive. Preliminary measurements of the superconducting transition in thin films of the high-temperature superconductorYBa2Cu3O7−&dgr;in magnetic fields up to 1.5 T are presented and discussed. They show a large field-dependent peak, attributable to tunneling effects, just below the onset temperature. Anomalies are also seen at higher temperatures, providing evidence of a structural phase transition. ©1997 American Institute of Physics.