The optical gas sensing properties of gold (Au) nanoparticles (NPs) doped into titanium dioxide (TiOmatrix prepared by sol鈥揼el method and annealed at different temperatures have been investigated. AFM images reveal that the Au NPs are exuded from the film during annealing. The chemical interaction of the hydrogen (Hand carbon monoxide (CO) molecules on the Au surface will increase the overall electron concentration on the metal side, cause a decrease in Au metal bulk plasma wavelength, and the surface plasmon resonance (SPR) peak can be used for the realization of a gas sensor with tunable sensitivity. The plasmonic responses are observed to be sensitive toward the presence of target gases. The results reveal that on decorating the Au NPs at the room temperature gas adsorption can be made possible due to the presence of Au NPs. We estimate that this kind of Au-NPs embedded in TiOfilm can be a promising material for nanophotonic and electrochemical sensor applications.