New negative temperature coefficient (NTC) ceramics based on CaCu 3−x Mn x Ti 4 O 12 (0≤x≤1) compositions have been investigated. The grain size of the CaCu 3−x Mn x Ti 4 O 12 samples decreases at first and then increases with increasing Mn content. The X-ray photoelectron spectroscopy analysis corroborates the presence of Mn 3+ and Mn 4+ in Mn-doped samples, which results in a decrease in the activation energy. All the NTC thermistors prepared show a linear relationship between the natural logarithm of the resistivity and the reciprocal temperature, indicative of NTC characteristics. The Mn-doped CaCu 3−x Mn x Ti 4 O 12 NTC thermistors provide various electrical properties, depending on Mn content. The values of ρ 25 , B constant and activation energy of the NTC thermistors are in the range of 2.22×10 6 –3.22×10 8 Ωcm, 5488–8031K, and 0.473–0.692eV, respectively.