Density functional theory has been used to investigate the binding of propene to small Ag clusters in the gas phase. The binding mechanism based on frontier orbital theory, which we used previously to describe the binding between propene and the Au clusters, works for the pure Ag clusters as well. Among other things, it explains the trends of the desorption energy of propene as a function of the Ag cluster size. We show that one can predict the binding site of propene by examining the shape of the lowest unoccupied molecular orbitals (LUMOs) of the bare clusters and correlate the strength of the bond to the orbital energies of the LUMOs of the bare cluster.