A new class of transition metal-carbon clusters named [open quotes]metallocarbohedrenes[close quotes] or [open quotes]met-cars[close quotes] with the stoichiometry M[sub 8]C[sub 12](M = Ti, V, Zr and Hf) has become the focus of intense investigation. In this communication, we report preliminary results on the reactivity of V[sub 8]C[sub 12][sup +] with O[sub 2] and provide evidence for the existence of two different metal atom sites consistent with the D[sub 2d] or T[sub d] structures. All of the experiments were performed on an Extrel FTMS-2000 dual-cell Fourier transform ion cyclotron resonance (FTICR) mass spectrometer combined with a compact supersonic source developed by Smalley and co-workers. The laser vaporization technique is used to generate metal-carbon clusters in a manner similar to that of Castleman and co-workers. The results presented here represent the first evidence of the high combustibility of V[sub 8]C[sub 12][sup +] in the presence of oxygen and lend further support to the T[sub d] or D[sub 2d] structure predicted by theory. The reactivity observed is also consistent with the predicted electronic structure indicating that V[sub 8]C[sub 12][sup +] is a high-spin species. 34 refs., 2 figs.