Abstract Objectives: The objective of this study is to investigate oxidation of three dyes: indigo carmine, methyl violet and 2, 4-dinitrophenol by two-component system Co 2+ -H 2 O 2 further analyzing behavior of cobalt in Fenton-like processes. Method: Oxidative degradation was effected in aqueous solutions of dyes under static conditions. Altering concentrations of substrates were analyzed spectrophotometrically. Dynamic light scattering was used to evaluate the condition of cobalt in the solution. The products of oxidative degradation were studied applying the method of nuclear magnetic resonance. Findings: The study shows that hydrogen peroxide in presence of ions Co 2+ is capable of oxidizing indigo carmine. The sulfate ions in the system do not affect the kinetics of the oxidation process. It has been found that oxidation supposedly occurs following the radical mechanism similar to the processes observed in the Fenton system (Fe 2+ - H 2 O 2 ). However, the range of pH values that makes oxidation possible differs considerably from the operating range of the Fenton system: With cobalt ions, the process runs at pH>6. It has been established that intensive oxidation of methyl violet and 2, 4-dinitrophenol also starts when рН value increases up to 6.6-6.8. The formation of cobalt-containing aggregates of cobalt hydroxides in the process of oxidative degradation of indigo carmine has been observed for the first time, i.e. the process occurs in ultra micro heterogeneous system. It has been shown that in presence of cobalt, the substrates are not oxidized in full; the products of oxidation are represented by a complicated set of organic compounds. Applications/Improvements: In practice, functioning at higher рН values is an important advantage of the cobalt-containing system as compared to the iron-containing one. Degradation of Some Dyes with Cobalt-Containing Oxidative System Olga Evgenievna Lebedeva * , Kirill Sergeevich Erokhin, Thuy Tran Thi and Kanagat Kazhmukhanovich Kishibayev Belgorod State University, Belgorod, Russia; OLebedeva@bsu.edu.ru; triamera-91@mail.ru; 691635@bsu.edu.ru; kanagat_kishibaev@mail.ru Key words: Cobalt Ions, Hydrogen Peroxide, Oxidative Degradation 1. Introduction Hydrogen peroxide is one of the most widely spread oxidizers that are used in developing Advanced Oxidation Processes implying liquid-phase degradation of organic contaminants by highly active radical particles. Such processes are studied extensively and are applied for the purposes of potable and waste water treatment. Generation of radical particles out of hydrogen peroxide increases redox potential of the system considerably. It is a well-known fact that radicals can be generated by way of introducing the ions of transition metals into the system, for example, ions of iron (II) 1 : Fe 2+ + H 2 О 2  Fe 3+ + ·OH + OH - Oxidative system that contains hydrogen peroxide and iron ions (the so-called Fenton system) has been studied profoundly. At the same time, the number of studies dedi- cated to investigating the interactions between hydrogen peroxide and ions of other iron triad metals is rather scarce. For example, there are three-component oxida- tive systems based on hydrogen peroxide, cobalt ions and ascorbic acid 2 . It is suggested that the system of cobalt ions – bicarbonate ions should be used for activating hydrogen peroxide 3 . ere are few publications dedicated to studying two-component oxidative systems containing hydrogen peroxide and cobalt salt. One of the studies 4 shows that the formation of radicals is preceded by the coordination of three molecules of hydrogen peroxide at one aquatic *Author for correspondence Indian Journal of Science and Technology, Vol 9(36), DOI: 10.17485/ijst/2016/v9i36/102021, September 2016 ISSN (Print) : 0974-6846 ISSN (Online) : 0974-5645