Abstract: Infrared spectra of ethylene chemisorbed on silicasupported palladium at 15℃ have been obtained.On hydrogenation of the chemisorbed surface species at 15℃, ethane and a smaller amount of n-butane were formed.The experiment indicated that ethylene chemisorbed on silicasupported palladium formed three surface species: the σ-bond type surface species PdCH₂CH₂Pd; the n-butyl type surface species CH₃ CH₂ CH₂ CH₂ Pd, probably via a self-hydrogenation and surface dimerization; and the surface carbide probably via the dissociative chemisorption of ethylene.