A fast, simple and reliable humidity sensor based on ion-doped SnO2 nanofibers has been developed by screen-printing on ceramic substrates with Ag-Pd interdigital electrodes in this research. The optimized results show that the impedance of the sensor decreases by more than five orders of magnitude with increasing relative humidity (RH) from 11% to 95%, the response and recovery time of the sensor are about 5 and 6s, respectively. Compared to the previous electrical conductivity-based SnO2 humidity sensors, the proposed sensor exhibits higher humidity sensitivity, more rapid response and recovery, smaller hysteresis, and better linearity and stability. (C) 2009 Elsevier B.V. All rights reserved.