Iodine is an essential nutrient in human diet, and it can be found in several foodstuffs. Several methods of iodine determination have been proposed, including ion-selective electrodes, X-ray fluorescence, inductively coupled plasma mass spectrometry, atomic absorption spectrometry and others. Iodine can also be determined by catalytic methods. There are two main employed methods. One is based on the redox reaction between cerium(IV) and arsenic(III). The second one consists in the catalytic action of iodide on the iron(III)-nitrite-thiocyanate reaction. The iron(III)-nitrite-thiocyanate reaction involves the catalytic action of iodide on the development of the iron(III)-nitrite and thiocyanate-nitrite reactions, the indicator being the excessive amount of iron(III):2Fe(III) +NO2- + H2O - 2Fe(II) +NO3 – + 2H+;(1)2SCN- + 3NO3- + 3NO2- + 2H+ –  2CN- + 2SO42- + 6NO + H2O; (2)Fe(III) + SCN- – Fe(SCN)2+. (3)The catalytic effect of the iodide increases directly with its concentration under the constant conditions of the reaction at temperature <313 k. This indicator system is normally used in analytical practice for the determination of iodine in the form of iodide by the kinetic spectrophotometric method at 313 K. When carrying out a large number of analyzes, observance of the indicated temperature conditions is inconvenient and energy consuming. The purpose of this work is to study the effect of anions, such as SO42-, Cl-, NO3- on the rate of the development of the iron(III)-nitrite-thiocyanate reaction and establish the optimum conditions for this reaction at room temperature. Certain parts of the solutions of the iodide, thiocyanate, iron(III) and, certain salts of mineral acids were pipetted into a series of polyethylene tubes and then water was added to a total volume of 8.0 cm3. Next to the start of the development of the catalytic reaction, 2.0 cm3 of solution of sodium nitrite was added and then mixed immediately. From this moment, by the stopwatch counted time, the solution was transferred into a cuvette of the spectrophotometer and immediately the absorbance was recorded every minute during 20 min. As the acceleration response grew up, the concentration of iron(III) (equation 1) and SCN- (equation 2) dropped, and as a result, the optical density of Fe(SCN)2+ solutions (equation 3) decreased as well. On the basis of the experimental data obtained and the information taken from literature, it can be assumed that the addition of salts of some mineral acids may cause changes in the coordination sphere of thiocyanate iron(III) complexes and, therefore, changes the redox potential of the system. This can also lead to either the deceleration or acceleration of the studied redox reaction. The rate of the catalytic iron(III)-nitrite-thiocyanate reaction correlates well with the complexing ability of the anions of strong mineral acids in relation to iron(III). The experimental conditions of the flow of the iron(III)-nitrite-thiocyanate reaction were optimized, which made it possible to determine iodine in the form of iodide at room temperature.