[en] A standard polarographic method was used to determine the formation curve for species in the cadmium-formate complex system. A semi-empirical correlation was established between the stability constants for the step-wise complexation reactions as follows: sup(β)n=A.asup(n)/n factorial. The stability constants were determined by an iterative procedure both with the constraint that the constants should be correlated and without this constraint. The resulting constants were used to calculate predicted formation curves which were then compared statistically with the measured curve and standard deviations determined. The same correlation was used to analyse published data on the glycolate complexes of the rare earths and the calculated stability constants compared with those published previously. In all cases the stability constants derived using the above correlation gave a satisfactory fit to the measured data. The fit was comparable to, though not usually as good as, that obtained by a more rigorous treatment of the data which does not assume that the constants are correlated. This correlation permits estimates to be made of the values of stability constants of higher complexes in a given metal-ligand system and to calculate the formation curve for all species if the stability constants of the first two complexes are known