In this paper spinel-type negative temperature coefficient (NTC) ceramic materials with general composition Ni0.6Mn2.4 xSnxO4 (x¼0.1, 0.2, 0.3, 0.4 and 0.5) were investigated. Powders were prepared by a solid-state reaction method and it was shown that the calcination temperature necessary for formation of the spinel phase as well as the lattice parameter increased with increasing Sn content (x). The specific resistivity at 25 1C and the B value of the ceramics increased sharply by adding more Sn. This increase was correlated with the distribution of the Sn4þ ions on the B-sites of the spinel lattice. The materials studied in this work are promising systems for NTC ceramics because of their high resistivity and B values.