Hydrogenation of acetylene in the presence of a large excess of ethylene has been investigated on the Pd-Ag catalyst at 60 degreesC with a space velocity of 2000 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 a certain amount of N2O added to 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. Upon aging, the pretreated catalyst exhibited good stability. (C) 2000 Elsevier Science B.V. All rights reserved.