The electronic density of states of epitaxial thin films of the Heusler compound Co2MnGa is probed in situ by spin-resolved ultraviolet photoemission spectroscopy. The experiments reveal several characteristic features in the intensity spectrum and a clear Fermi edge signature. A high spin polarization of similar or equal to 55% at the Fermi edge is followed by a sign change at the binding energy of similar or equal to 0.8 eV. Corresponding calculations of the band structure and the photoemission spectrum were performed employing a spin-polarized relativistic Korringa-Kohn-Rostoker code. Good agreement between the experimental data and calculations was obtained, including dynamical correlation effects.