Precursor powder of calcia-stabilized zirconia (CSZ) with 4, 7 and 15 wt % was synthesized by mechanical alloying (MA) in cryogenic conditions. The phase evolution of the precursor powders over 100 hours of MA was analyzed by powder X-ray diffraction technique. Cylindrical shaped sensor elements of the calcined powders were fabricated in a uniaxial press followed by sintering at 15000C for 3 hours. Scanning electron microscopy (SEM) was used to analyze the microstructure of the sintered pellets. The co-relation between material compositions, microstructure of the sinter pellets and the electrical properties of the sensors are discussed.