Abstract
Electron energy‐loss spectroscopy is used to examine the surface intermediates formed during ethylene hydrogenation on platinum at 298 K. We find that during the reaction the surface is covered with a mixture of ethyl radicals and ethylidyne. The ethyl radicals can be easily hydrogenated off the surface suggesting that they may be reactive intermediates. However, the ethylidynes are stable suggesting that they are spectators in the reaction.