In this paper, the distribution of cerium (IV) species depending on the charges of nitric acid-perchloric acid concentration at constant ionic strength (I=1.0) was investigated. Cerium (IV), being a strong oxidant, was utilized for investigating the oxidation kinetics of some amino acids. Knowing the distribution of cerium (IV) species is beneficial for better understanding this type of kinetics. Distribution of cerium (IV) species in aqueous media was studied by measuring the total optical absorbance of cerium (IV) species in different nitric acid-perchloric acid mixture solutions. The stability constants (K-1 and K-2) of the nitrate cerium complexes were determined spectrophotometrically from equilibrium data and from kinetic data concerning the eerie oxidation of amino acids. The magnitudes of the constants computed by these two separate methods were in accordance with each other.