In an attempt to improve the understanding of the electrochemical effects observed on an original potentiometric gas sensor, interactions of oxygen with the device were investigated. These calorimetric measurements have evidenced the existence of a weakly bounded endothermal oxygen species. Moreover these species may be regarded to be responsible for the electrical response developed by the sensor. Such results, which are in agreement with a previously proposed model, validate the underlying hypothesis and shed light on the role of oxygen in the sensor's responses.