We have studied the transferability of EXAFS amplitudes between carbon and oxygen as backscattering atoms. EXAFS data were collected on model compounds of known structure. The empirical phase and amplitude functions derived from an oxygen coordination shell were used as references to analyze a carbon coordination shell, and vice versa. It was found that the coordination numbers obtained from EXAFS analysis differ significantly from the real coordination numbers, showing that the backscattering amplitudes are not transferable for low-Z elements e.g. oxygen and carbon.