We present the use of three silane reagents in the vapour phase to react with the surface of magnesium and compare their performance against uncoated material using an accelerated corrosion test. The influence of atmospheric exposure on the corrosion test was also considered and rationalised based on previous models of the magnesium surface. XPS analysis determined that the silanes coated the surface of the metal; the accelerated gas evolution test showed very good corrosion inhibition properties for triethoxy(1H,1H,2H,2H-perfluoro-1-octyl)silane (FSil) in comparison with 3-aminopropyltriethoxysilane (APTE) and the uncoated material. The surface functionalisation using vapour proves to be an effective solvent free method of engineering oxide surfaces.