The negative temperature coefficient material with low thermal constant B and high resistivity were explored for low-temperature thermistor applications. The spinel oxide Fe0.5Cu0.2Ni0.66Mn1.64O4 had a required low B value, but its resistivity was much lower than the required value. To increase the resistivity, yttrium-stabilized zirconia (YSZ) was introduced into the spinel oxide. The spinel oxide in composite with YSZ (80 mol%) exhibited a much increased resistivity (10 479 center dot cm at 25 degrees C) while without causing much change in the B value (2842 K). It was found that the electrical conduction of the composite can be described quantitatively using the percolation theory.