This work reports the reactions of NaCo (CO)₄ with GeCl₄, GeBr₄, MeGeCl₃, MeGeBr₃, and Me₂GeCl₂ and of Co₂(CO)₈ with germanium hydride derivatives, along with the isolation and characterisation of their products. Amongst these are the new compounds ClGe[Co(CO)₄]₃, Br₂Ge[Co(CO)₄]₂, BrGe[Co(CO)₄]₃, MeGeCl₂Co(CO)₄, MeGeBr₂Co(CO)₄, MeGeCl[Co(CO)₄]₂, MeGeBr[Co(CO)₄]₂, GeCo₄(CO)₁₄ and Ge[Co(CO)₄]₄. There have also been indications of MeGe[Co(CO)₄]₃ and some spectroscopic data have been collected for Me₂GeBrCo(CO)₄. The proposed configuration for GeCo₄(CO)₁₄ is a novel extension of the already-established germanium – bridged dicobalt carbonyl derivatives. The relationships between and interconversions of three tetracobalt derivatives of Germanium are discussed. A review of Group IVB - Cobalt carbonyl derivatives is presented along with a discussion of the mass and infrared spectra of compounds prepared in this work. Some of the chlorogermyl cobalt carbonyl derivatives prepared in this work have been reacted with NaMn(CO)₅. Under this competition situation, metal carbonyl exchange has been found to be favoured over alkali halide elimination. e.g. : ClGe[Co(CO)₄]₃ + 3NaMn(CO)₅ → ClGe[Mn(CO)₅]₃ + 3NaCo(CO)₄ However, this system is subject to substituent effects. Preliminary studies on the Germanium derivatives of Rhenium and Vanadium carbonyls are also reported.