High-temperature electrochemical sensors based on stabilized zirconia play an important role in the control of exhaust emissions and the improvement of product quality and productivity. This paper gives an overview about high temperature oxygen sensor, auxiliary electrode type sensor, and mixed potential gas sensor. The response theories of a variety of sensors are elucidated. The related measurement ranges and application examples of oxygen sensors are presented. Since air pollution regulations are being reinforced in many countries, the worldwide demand for oxygen sensors is expected to be growing. Without appropriate solid electrolyte, auxiliary electrode type sensors are developed for measuring phosphorus, sulfur, silicon, manganese and chromium in melt and CO2, NOx and SOx in gas. We have described recent advances in improving the sensitivity, selectivity and long-term stability of mixed potential gas sensors which could be obtained by selecting suitable SE materials. This paper also reviews the limiting factors in measurement, the properties of stabilized zirconia and the role of electrode configuration in electrochemical sensors. (C) 2015 Elsevier B.V. All rights reserved.