The formation of Self-Assembled Monolayers (SAMs) by specific organic molecules with appropriate anchor groups on semiconductor surfaces may be used to probe the chemical state and quality of the surface or to achieve surface passivation. Molecules with thiole anchor groups are capable to bond via a Ge-S bond to hydrogen-terminated germanium surfaces. We have prepared SAMs of alkylthioles with different head groups on germanium. Since the surface preparation of germanium is not well understood and developed the controlled preparation of an oxide-free completely H-terminated surface turned out as major challenge and prerequisite for SAMs formation of alkylthioles. Several approaches have been studied. The HF treatment provided the most promising results. Nevertheless the maximum coverage by SAMs achieved was 50 % depending on the preparation conditions. The characterization of the germanium surface prior to and after SAMs formation has been performed by AFM, XPS and TXRF.