U-graphite intercalation compound (GIC) was prepared in-situ by deposition of U metal onto single-crystalline graphite(0001) and subsequent annealing. The samples were studied by angle-resolved photoemission (PE) and resonant PE at the 5d --> 5f excitation threshold. From a comparison of the experimental data with results of our LDA-LCAO calculations, the electronic structure of the GIC may be understood in a first approach by a charge transfer from the U atoms to unoccupied pi(0)* orbitals of graphite. The latter is related to a shift to higher binding energies of all graphite-derived PE features and appearance of an additional rather narrow feature at the Fermi energy upon intercalation. This Fermi-level peak is superimposed by a sharp U 5f signal, that reveals no trace of multiplet splitting. Since our results give clear evidence for a localized character of the U 5f states, we assume that U is mixed-valent in this compound.