Indirect ligand exchange methods have been demonstrated to replace the oleylamine capping with dodecanethiol for germanium nanocrystals (Ge NCs). In these methods, hydrazine is employed to effectively remove the oleylamine ligand before the NCs are passivated by microwave-assisted heating with dodecanethiol. In this work, octadecanethiol passivation is accomplished by the in situ reaction of dioctadecyl disulfide with diphenylphosphine. ¹H NMR and FTIR are used to characterize the surface ligand capping and the effectiveness of ligand exchange. Thiol passivation is achieved either by an exchange reaction at room temperature or by using microwave-assisted heating. Indirect and direct ligand exchange methods are demonstrated to be effective. The microwave-assisted reaction of GeI₂ with dioctadecyl disulfide also achieves thiol passivation without interfering in the formation of Ge NCs. Additional experiments study the effects of nanoparticle synthesis temperature, solvent, and ligand concentration on the exchange of oleylamine for octadecanethiol ligands.