Solid electrolyte sensor for detecting a sulfurous component in a gas stream

A sulfur-detecting sensor for detecting a sulfurous component contained in a substantially oxygen-free gas stream, the sensor comprising a solid electrolyte substrate through which oxygen ions can move, and electrodes for detecting a difference in potential induced by a electrochemical reaction of oxygen ion moving through the solid electrolyte substrate with a component constituting the gas stream, which electrodes for detecting a difference in potential include a detecting electrode formed on one side of the solid electrolyte substrate and brought into contact with the gas stream, and a reference electrode formed on the other side of the solid electrolyte substrate and brought into contact with an oxygen-containing fluid, the detecting electrode being formed from a transition metal having an enthalpy of formation of sulfide of not smaller than -250 kJ/mol at 25°C, or an oxide thereof. A sulfur-detecting device comprising the above sensor and a voltmeter for measuring a potential difference between the detecting electrode and the reference electrode of the sulfur-detecting sensor is also disclosed.