Microcrystalline mixture of fullerene dimer oxides (C120On, n = 1, 2, 3,...) was extracted from decomposed C60Br24 Low-temperature FTIR studies of the product showed the absence of orientational ordering transitions indicating freezing of C-60 rotations due to inter-cage bonding and epoxidation. Characteristic features due to inter-cage vibrations are seen in the far IR spectrum. Bond cleavages in MS/MS leave all the oxygen atoms of the dimer oxide with one fullerene molecule. We propose that dimers are formed by [3 + 2] cycloaddition of C60 With its oxides, C60On rather than cycloaddition of the monomeric oxides. Results are discussed based on the possible reaction sequences.