Wafer scale arrays of nanostructured titania (NST) sensing elements have been fabricated using standard microfabrication techniques. Sensing elements are 20 mu m on a side and formed by the oxidation of titanium thin films in aqueous hydrogen peroxide. NST elements are highly sensitive to oxygen, but only slightly sensitive to hydrogen. High sensitivity to hydrogen is achieved by modification of the sensors with platinum. A platinum salt solution is introduced to the NST sensor elements and subsequently thermally decomposed. When exposed to 10 mT of hydrogen at 250 degrees C, the functionalized devices exhibit over a one-order-of-magnitude resistance decrease with a response time of similar to 7 s; conversely, unmodified NST exhibit little, if any, response under the same conditions. Proposed sensing mechanisms of the NST elements are briefly discussed. (C) 2008 The Electrochemical Society.