Free standing assemblies of carbon nanotubes (CNTs), known as bucky-paper (BP), have been functionalised through the in situ plating of gold nanoparticles within the interstitial spaces in the BP. The nanoparticles are extremely small and well distributed at short plating times, so much so that the specific surface area of the BP is actually increased by the gold incorporation. These well distributed nanoparticles exhibit high enthalpy hydrogen storage and selective carbon dioxide adsorption over other gases, in particular methane. In concert with the conductive BP substrate, it has been demonstrated that these materials can also act as high turnover heterogeneous catalysts.