This paper reports about the synthesis and characterization of a novel Fe/Fe2O3/polyoxocarbosilane core shell nanocomposite as a material for gas-sensing applications. The nanocomposites (Fe-based nano cores enveloped with polymeric polyoxocarbosilane shells) were prepared by the IR laser co-pyrolysis of iron pentacarbonyl and hexamethyldisiloxane. The iron-based cores become superficially oxidized in atmosphere. The morphologies, chemical content and thermal behavior were studied by different analytical techniques. The sensing properties of the polymer-poor nanocomposite thick films were tested by measuring the variation of the electrical resistance in presence of CO and CH4, at a working temperature of 450 degrees C. Preliminary results indicate that for CO toxic gas, an n-p transitional character of the semiconducting iron oxide appears in humid relatively to dry air.