Silicon nanowires (Si NWs) terminated with methyl functionalities exhibit higher oxidation resistance under ambient conditions than equivalent 2D Si(100) and 2D Si(111) surfaces having similar or 10–20% higher initial coverage. The kinetics of methyl adsorption as well as complementary surface analysis by XPS and ToF SIMS attribute this difference to the formation of stronger Si–C bonds on Si NWs, as compared to 2D Si surfaces. This finding offers the possibility of functionalising Si NWs with minimum effect on the conductance of the near-gap channels leading towards more efficient Si NW electronic devices.