Cu–Zn alloy nanoparticles in mass production are synthesized through a wire electrical explosion (WEE) method. The atoms on the surface of the as-synthesized nanoparticles are oxidized to form the Cu–Zn/CuO–ZnO nanoparticles (CZ/CZNs). The humidity sensing properties of CZ/CZNs and KCl-doped Cu–Zn/CuO–ZnO nanoparticles (KCZ/CZNs) are investigated by screen-printing them on ceramic substrates with Ag–Pd interdigitated electrodes, respectively. The measurement results show that KCZ/CZNs hold the improved humidity sensing properties with the impedance varying about four orders of magnitude in the range of 11–95% relative humidity (RH), while the impedance of CZ/CZNs changes only about two orders of magnitude. The response and recovery time of KCZ/CZNs are about 40 and 50 s, respectively. And the maximum hysteresis is around 4% RH. Our results demonstrate the potential application of KCZ/CZNs for fabricating high performance humidity sensors.