We have chosen six ML2 complexes, with a systematic variation in the ligands and metals, to investigate oxidative additions as well as reductive eliminations by using the MP2/LANL2DZ and the MP4SDTQ//MP2/LANL2DZ levels of theory. A qualitative model based on the theory of Press and Shaik (Su, M.-D. Inorg. Chem. 1995, 34, 3829) has been used to develop an explanation for the barrier heights. Considering the geometrical effect, the substituent effect, and the nature of the metal center, the following conclusions emerge : for 14-electron ML2 complexes, a smaller L-M-L angle and a better electron-donating ligand as well as a heavier transition metal center (such as Pt) should be a potential model for the oxidative addition of saturated C-H bends. Conversely, a linear structure and a better electron-withdrawing ligand as well as a lighter transition metal center (such as Pd) would be a good candidate for reductive coupling of C-H bonds. The results obtained are in good agreement with the available experimental results and permit a number of predictions to be made.