A thick-film humidity sensor has been fabricated by depositing a humidity sensitive layer between two metal electrodes on Al2O3 substrate. The performance of this "sandwich"-configured humidity sensor depends not only on the middle sensing layer itself but also on the properties of its electrode materials. The influence of electrode materials on the characteristics of a thick-film ceramic humidity sensor is described in this paper. A thick-film humidity sensor with platinum electrodes exhibits, in general, a higher sensitivity in the whole humidity range and a shorter response time than that with Ag/Pd electrodes. Moreover the humidity sensor with Pt electrodes shows excellent stability while a sensor with Ag/Pd electrodes has a poor duration due to Ag+ migration in a moisture environment.