New nickel oxyhydroxide/palladium (NiOOH/Pd) nanocomposites was prepared and showed novel gasochromic characteristics for the first time. The NiOOH microparticles were obtained using the chemical bath synthesis method without stirring for 72 h. The synthesized catalytic palladium nanoparticles (PdNPs) were added into the NiOOH microparticles and the NiOOH/Pd nanocomposites were readied for gasochromic application. The NiOOH/Pd nanocomposite thin film was obtained by using wet-coating methods. An obviously color change from black state NiOOH to white state Ni(OH)(2) was observed after exposed to hydrogen (H-2), the maximum transmittance change was 23.2% at 572 nm. The white Ni(OH)(2) state can be switched back to darken state by exposing to ozone (O-3) on the thin film with its novel gasochromic property. Surface electron microscopy (SEM) images showed special surface morphology of NiOOH/Pd before and after gas treatments. Xray photoelectron spectroscopy (XPS) analysis was used to confirm the changes in chemical bonding before/after gas treatment. XRD patterns and FT-IR spectra indicated the structure changes that occurred during film preparation and before/after exposed to H-2.