A convenient but rigorous method for evaluating the stability constants of complexes of the mixed-ligand type has been proposed and applied to the determination of the stability constants β_ij of UO₂A_i(OH)_i from distribution data. It is found that in the pH range studied there exist five uranyl species in aqueous phase, namely, UO₂²⁺, UO₂A⁺, UO₂A₂, UO₂(OH)⁺, and UO₂(OH)A, where A-represents the benzoate ion, with the following stability constants.