Chemisorption of hydrocarbons on metallic nanoparticles represents a fundamental step in catalytic processes of industrial relevance such as epoxidation reactions. In this work we study the adsorption of a simple unsaturated hydrocarbon (1-hexene) by gasborne silver and gold nanoparticles. Both kinds of metallic nanoparticles were produced by evaporation and condensation in a nitrogen flow, but using different methods. The uptake was determined by measuring the change of the mobility diameter of size selected 10 nm particles using a Tandem-Differential Mobility Analysis (T-DMA) setup. While no uptake of hexene by gold could be measured, the uptake on silver showed to be both concentration and temperature dependent. The uptake showed a maximum at a temperature of 170 +/- 10 degrees C. The addition of oxygen was evaluated and its presence did not alter the results. FT-IR measurements confirmed the adsorbed state of 1-hexene on silver.