Hydrogenation of acetylene in the presence of a large excess of ethylene has been investigated on the Pd-Ag catalyst under 60 degrees C and a space velocity of 2,000 h(-1). It was found that an enhancement in the performance of Pd-Ag catalyst can be obtained by pretreatment with N2O. It is suggested that added N2O on the catalyst before use not only augments the sites associated with ethylene production from acetylene but also depletes the sites responsible for direct ethane formation.