We have developed a planar type NOx sensor with a dense sensing layer that consists of nano-size grains and a reference electrode buried in an electrolyte by a pulsed laser deposition method, and examined for the mixed-potential-type NOx sensor. This sensor shows a high NO sensitivity at low temperature (300-450 degrees C). Electromotive force (EMF) values were almost linear to the logarithm of NO concentration, and the response was reproducible. The magnitude of EMF response was about -90 mV upon exposure to 1000 ppm of NO at 350 degrees C. And, the 90% response and recovery times were found to be about 5 and 25 s at 450 degrees C, respectively. This cell opens up the possibilities for development of an integrated electrochemical device for NOx gas treatment in combustion exhausts. (C) 2008 Elsevier B.V. All rights reserved.