The structures, vibrational frequencies, enthalpies of formation, and dissociation energies of germane, chlorinated and fluorinated germanes, and their radical fragments have been examined with density functional theory and quantum chemistry ab initio methods. The theoretical vibrational frequencies of the germanes at the B3LYP/6-31G(2df,p) level are in good agreement with the experimental data, but those of the germyl radicals largely disagree with the previous experimental assignments. The G3//DFT enthalpies of formation of GeH4, GeCl4, and GeCl2 are within two times of the experimental uncertainties, while that of GeF4 differs with the experiment by similar to10 kJ/mol. The calculated enthalpies of formation of the Ge-containing radicals have a large discrepancy with the available experimental data (which have large uncertainties). The bond dissociation energies of the Ge species and their trends with the F/Cl substitutions are evaluated at the G3 level as well. For dissociation of partially substituted F/Cl-germanes and germyl radicals, a propensity of diatomic elimination of H-2 or HF/HCl over single bond breaking is suggested, based on the low-energy barriers of the diatomic eliminations relative to the bond breakage to form Ge-containing radicals.