The complex species formed between chromium(III) picolinic and chromium(III) dipicolinic acids and small blood serum bioligands such as lactic, oxalic, citric, and phosphoric acids were studied in aqueous solution by means of electromotive force measurement emf(H) at 25 degrees C and 1.5 mol center dot dm(-3) KCl as the ionic medium. The binary and ternary complexes were studied by the aging solution method, consisting of the preparation of different molar ligand/metal ratios at different pH values: solutions were maintained at room temperature (25 +/- 1 degrees C) for 45 days; potentiometric measurements were then done; and the data were analyzed by means of the least-squares computational program LETAGROP, obtaining the respective stability constants and the stoichiometric coefficients of the complexes formed in aqueous solution.