This invention provides an oxygen concentration detecting element and method of producing the same for use in detecting the oxygen concentration of gases such as exhaust gases from gasoline engines. The oxygen concentration detecting element is characterized by a shaped and sintered porous body consisting essentially of semiconductor materials and platinum particles dispersed at an average particle-to-particle spacing of no more than 10 .mu. throughout said element.The element has high durability and non-hysteresis characteristics, and can be used over a wide temperature range. The element is especially useful in detecting the oxygen concentration of an exhaust gas.