The spectral characteristics of the iron(III) lactate complexes were examined by the spectrophotometric methode, and the absorbance of these complexes has been studied at diferente wavelengthes . The stoichiometry of the photoreactive complex formed in the iron(III)-lactate system has been investigated in aqeuous solution under determinative experimental conditions. Initial concentrations whether of Iron(III) or of lactic acid ranged from to , and -values were belonging to the range . The results showed, that the ratio of iron(III) to lactate in the photoreactive complex is 1:2, i.e. its formula is . This complex has a maximum absorption at 365 nm. Its molecular absorption coefficient is about ≈ and its dissociation constant is about . The tentative mechanism for the photochemical decomposition of the complex has been suggested, in agreement with the reference studys . The suggested mechanism depends on the relationship between the absorbance and the photoreaction kinetics, and it is not based on the qualitative or quantitative analysis of reaction products.