Nanostructured indium oxide thin films were prepared by spin-coating the precursor solution on highly porous substrates. Porous substrates were prepared by modifying the surface of glass substrate using poly (methylmethacrylate) solution. Scanning electron microscopic images of the films coated on modified glass substrates show algae-like growth which occupies a larger surface area when compared to the films coated on unmodified substrates which is in accordance with the atomic force microscopic images. Gas sensing property of the films coated on modified substrates showed notable sensitivity even at room temperature. The sensor response for ammonia and ethanol is around 1.8 and 1.5 respectively. (C) 2010 Elsevier B.V. All rights reserved.