ZnO nanorods prepared by two different procedures and ZnO nanowires prepared by electrochemical deposition in alumina membranes as well as ZnO nanotubes have been investigated for hydrogen and ethanol sensing characteristics. The sensing characteristics of these nanostructures were also investigated after impregnating them with 1% Pt. The nanowires exhibit excellent hydrogen sensing characteristics at relatively low temperatures (<= 150 degrees C) specially when impregnated with Pt. One type of nanorods shows a satisfactory dependence of sensitivity on the hydrogen concentration, along with short recovery and response times. The nanorods and nanowires impregnated with Pt also show high sensitivity for 1000 ppm of ethanol at or below 150 degrees C, with short recovery and response times. (c) 2005 Elsevier B.V. All rights reserved.