The metallicity of lithium rich LinHm+ cluster ions [1 less than or equal to m less than or equal to 6, n less than or equal to 22, and (n - m) > 3] is studied by measuring unimolecular dissociation rates, These clusters are found to decompose by evaporation of a Li atom or a Li-2 molecule. The evaporative rates of mixed clusters display features characteristic of metallic clusters. This confirms and extends to a larger size range the previous results obtained by photoionization and absorption cross-section measurements. The simulation of the evaporative rates. with a statistical Rice-RamsperEer-Kassel (RRK) model which has been adapted to mixed clusters, confirms that there is a clear separation between a metallic Li-n-m(+) part and an insulating (LiH)(m) part.