An amperometric sensor for monitoring ethanol concentration using a Ni-Pt alloy electrode has been developed. The films of Ni-Pt alloy were electrodeposited under various potentials on an Au/Al2O3 substrate. To examine the effects of Ni-Pt alloy films on the sensing performance, the electrodes with various Ni:Pt atomic proportions of 100:0, 25:75, 70:30, 82:18 and 0: 100 were prepared and tested. X-ray diffraction and scanning electron microscope analyses indicate that Ni atoms of Ni-Pt alloy electrodes are inserted in the Pt lattice and a pyramid-like structure is formed with an increase of Pt content in the film. All the prepared electrodes have a linear relationship between response current and ethanol concentration for the detection range of 50 to 300 ppm ethanol in alkaline solutions. With an increase of Pt content in the film, the response time of the Ni-Pt alloy electrodes was reduced whereas the sensitivity was decreased. The sensor with 70 at.% Pt in the film was most stable with the duration over a 63-day-period. The sensitivity of the Ni-Pt alloy electrodes for detecting glucose, various alcohols and acids have also been studied. (C) 2007 Elsevier B.V. All rights reserved.