This work reports the unusual results on studying the operability and capability of a solid state electrochemical sensor based on a proton-conducting material to analyze the oxygen concentration in a gas media at elevated temperatures. This sensor consists of two ceramic parts made of CaZr0.9In0.1O3-delta, one of which acts as a hydrogen pump element, while another as a potentiometric detection element. A limiting current, occurring at a certain voltage value applied to the former element, is a sensor's response; it forms the concentration or temperature calibration curves, which can be used for the subsequent electrochemical analysis at high temperatures. The presented results expand the possibilities for utilizing the proton-conducting materials in new electrochemical (analytical) directions.