The following thesis describes the exploration of lithium endohedral fullerenes (Li@C₆₀) on Au(111) and Cu(110)-(2×1)O utilising an ultra-high vacuum low temperature scanning tunnelling microscope (UHV LT-STM). In collaboration with researchers from the University of Edinburgh and the University of Liège, the effect of Li-encapsulation on the electronic structure of C₆₀ has been experimentally identified on single molecules for the first time, with particular attention to the superatom molecular orbitals (SAMOs). It was hypothesised these would...