The initial stages of intercalation are explored by investigating the electronic changes occurring on evaporation of alkali metal overlayers onto both single-crystal and highly oriented pyrolytic graphite (HOPG). In the case of ordered (2 × 2)R0° overlayers of Cs and K we clearly demonstrate that the outer alkali metal s-electron is completely transferred to the graphite conduction band. Identical results are obtained from a K "intercalation compound" prepared by in situ room-temperature K. evaporation. Preliminary results from overlayers of Li and Na indicate that the behaviour of these lighter alkali metals is somewhat different. The evaporated Li appears to be mobile, and intercalates, even at the lowest temperatures available in this experiment (100 K). whilst Na, which does not readily form graphite intercalation compounds, displays an incomplete charge transfer.