A density functional study of some silver cluster hydrides of general formulae AgnH is presented, in order to help the identification of species possibly formed in the interior of zeolites. Two correlation-exchange functionals were employed with two different basis sets and effective core potentials in order to investigate their influence on the final results. The calculated frequencies of the Ag-H stretching modes suggest that this property could be used to help the characterization of the silver hydride species formed inside zeolites. (C) 2004 Elsevier B.V. All rights reserved.