Basic characteristics of a simple single-flux-quantum (SFQ) logic gate using high-Tcmaterial and Josephson junction (NdBa2Cu3O7−&dgr;and focused ion beam junction) have been investigated. The logic gate consists of an rf-superconducting quantum interference device (rf-SQUID) and a dc-SQUID. In the logic gate, elementary SFQ logic operations, such as generating SFQ (dc/SFQ) and providing simultaneous readout (SFQ/dc), have been confirmed up to 50 K. The temperature dependencies of the output voltage level and the critical current-normal resistance(IcRn)product were compared, and the decreasing tendency of the output voltage level for increasing temperature was found to be more rapid than that of theIcRnproduct. ©1998 American Institute of Physics.