It was found for the first time that high temperature negative temperature coefficient (NTC) composites ceramic of La1-xMgxTiO3 (x = 0.1, 0.3, 0.5, 0.7, 0.9) have been prepared by the solid-state reaction method sintered at 1400 degrees C. The effects of MgTiO3 and LaTiO3 composites on the structure, electrical properties and stability of the sintered ceramic samples were characterized by thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), Mapping, X-ray photoelectron spectroscopy analysis. XRD patterns analysis has revealed that for La1-xMgxTiO3 (x = 0.1, 0.3, 0.5, 0.7, 0.9) the major phases presents in the calcined bodies are double perovskites the LaTiO3 phase and the MgTiO3 phase. The SEM images have exhibited that as the mole fraction of Mg2+ from 0.1 to 0.9, the grain size of the MgTiO3 ceramics increases from ca. 1.77 to 5.99 mu m and LaTiO3 ceramics decreases from ca. 2.83 to 1.53 mu m. X-ray photoelectron spectroscopy prove the Ti3+ and Ti4+ ions on lattice sites, which result in hopping conduction. The presence of the Ti3+ and Ti4+ ions is one of the significant factors that affect the electrical conductivity of La1-xMgxTiO3 composites ceramic. The rho(400) and B-400/1200 values are in the range of 14,693.137-65,659.809 omega center dot cm and 7785.270-24,948.100 K, respectively. The La1-xMgxTiO3 materials could be used as potential candidates for high temperature range from 400 to 1200 degrees C thermistors applications. The resistance variation (Delta R/R-0) was < 2% and the minimum value (0.1%) was obtained for aging at 1100 degrees C at 800 h. The aim of this work was exploring new composite ceramics materials, which could be used as higher temperature zones.