The reaction of solid C58 films with atomic deuterium to yield deuterofullerenes, C58Dx, has been investigated by thermal desorption spectroscopy coupled with mass spectrometric detection, ultraviolet photoionization spectroscopy (21.2eV), and atomic force microscopy (AFM). The average composition of the deuterofullerenes created depends on deuterium dose, beam flux, and surface temperature. Low deuterium exposures at room temperature yield predominantly C58D6–8 cages. Saturation exposures at room temperature yield mass spectra peaked at C58D26. After saturation exposures at elevated surface temperatures (∼500K), the (subsequently) desorbed material reveals a comparatively narrow mass spectral distribution centered at C58D30. Deuteration is associated with cleavage of covalent cage-cage bonds in the starting C58 oligomer material, as evidenced by a considerable lowering of the sublimation energies of C58Dx compared to desorption of C58 desorbed from pure oligomer films. Correspondingly, AFM images reveal a D-induced, thermally activated transition from dendritic C58 oligomer islands into smooth-rimmed islands composed of deuterated cages. Deuterated films exhibit a significantly lower work function than bare C58 films. Progressing deuteration also gradually raises the surface ionization potential.