The thermal stability and sensitivity of a new n + p structure oxygen sensor were studied from the theoretical viewpoint. The results show that when the two sensing materials meet certain conditions, the new type oxygen sensor not only has a higher sensitivity to oxygen than the conventional oxygen sensor (i.e. n-type or p-type single-disc oxygen sensors), but also solves a major problem that the characteristics of conventional oxygen sensors are affected by temperature drift. (C) 2002 Elsevier Science Ltd. All rights reserved.