Zr-substituted SnO 2 -based ceramics (Sn 0.95-x Sb 0.05 Zr x O 2 , x B 0.1) were prepared by using a wet-chemical synthesis method. The results show that the prepared ceramics have a pure tetragonal phase as that of SnO 2 and have a typical characteristic of negative temperature coefficient (NTC) of resistivity over a wide temperature range from -50 to 300°C. The room-temperature resistivity q 25 and material constant B 25/85 of the NTC thermistors increase from 4.77 X cm to 4.89 9 10 7 X cm and from 641 to 5085 K, respectively, when the content of Zr, x, changes from 0 to 0.1. The NTC thermistors also show high cyclic stability and ageing resistance. The analysis of impedance spectra reveals that the NTC effect mainly resulted from the grain-boundary contribution, and the conduction mechanisms of the Sn 0.95-x Sb 0.05 Zr x O 2 thermistors combine with the electron-hopping conduction and band conduction.