Ion-exchange uranium-citrate experiments were performed to evaluate the formation of the uranium-citrate and uranium-iron-citrate complexes over a wide concentration range; i.e., environmentally uranium-iron-citrate relevant concentrations (e.g., 10(-6) M in metal and ligand) and concentrations useful for spectroscopic investigations (e.g., 10(-4) M in metal at and ligand). The stability of the well-known uranium-citrate complex was determined to validate the computational and experimental methods applied to the the more complex system. Values of the conditional stability constants for these species were obtained using a chemical equilibrium model 8.71+/- .6 in FITEQL. At a pH of 4. , the stability constant for uranium-citrate complex (log beta1,1) was determined to be 8.71+/- .6 determined at I = . Analysis of the results of ion-exchange experiments for the U-Fe-citric acid system indicates the formation of The the 1:1:1 and 1:1:2 ternary species with stability constants (log beta) of 17.10+/- .41 and 20.47+/- .31, respectively, at I= .