An optical gas sensor with a light-emitting diode (2), a photosensor (8), a measuring section between the light-emitting diode and the photosensor, and a control and analyzing unit (16), which is set up to determine the concentration of a gas in the measuring section from the light intensity measurement by the photosensor. The control and analyzing unit (16) is set up to measure the forward diode voltage over the light-emitting diode at a constant current, to determine the temperature of the light-emitting diode from the detected forward diode voltage over the light-emitting diode by means of a preset temperature dependence of the forward diode voltage, and to apply a correction function as a function of the light-emitting diode temperature determined, with which the measurement is converted to that of a preset temperature of the light-emitting diode.