The sticking probability and heat of adsorption for C 2 H 4 on the stepped Pt{211} and Pt{311}-(1x2) surfaces have been measured for the first time. Adsorption on Pt{211} leads to the formation of several different species as a function of coverage, whereas adsorption on Pt{311}-(1x2) leads to the formation of only one species on the surface over the whole coverage range. The initial heats of adsorption for C 2 H 4 on Pt{211} and Pt{311}-(1x2) have been measured as 180 and 220kJmol - 1 , respectively. The initial sticking probabilities are 0.84 for both surfaces. The most likely species to be formed on Pt{211} as a function of coverage are quad-σ acetylene followed by ethylidyne whereas on Pt{311}-(1x2) ethylylidyne forms at all coverages.