Recent electrochemical evidence appears to indicate that in the solid state it is possible to obtain a stable compound of stoichiometry Li12C60. Prompted by these findings we have investigated by ab initio molecular dynamics the possibility that Li12C60 might exist as a stable cluster. Our results show that a structure with Ih symmetry is stable, which also corresponds to a HOMO-LUMO gap of the same order as that of C60. The presence of the Li atoms induces a polarization of the electronic states of the cage, and gives rise to a significant weakening of the double bonds. From a molecular dynamics simulation we compute the frequencies of the optically active vibrational modes. © 1992.