Oxidation of unsymmetrical dimethylhydrazine (UDMH) during a water treatment has several disadvantages including formation of stable toxic byproducts. Effectiveness of treatment methods in relation to UDMH transformation products is currently poorly studied. This work considers the effectiveness of chemical oxidants in respect to main metabolites of UDMH – 1-formyl-2,2-dimethylhydrazine, dimethylaminoacetontrile, N-nitrosodimethylamine and 1-methyl-1H-1,2,4-triazole. Experiments on chemical oxidation by Fenton's reagent, potassium permanganate and sodium nitrite were conducted. Quantitative determination was performed by HPLC. Oxidation products were identified by gas chromatography-mass spectrometry in combination with solid-phase microextraction. 1-Formyl-2,2-dimethylhydrazine was completely oxidized by Fenton's reagent with formation of formaldehyde N-formyl-N-methyl-hydrazone, 1,4-dihydro-1,4-dimethyl-5H-tetrazol-5-one by the action of potassium permanganate and N-methyl-N-nitro-methanamine in the presence of sodium nitrite. Oxidation of 1-formyl-2,2-dimethylhydrazine also resulted in formation of N-nitrosodimethylamine. Oxidation of dimethylaminoacetontrile proceeded with formation of hydroxyacetonitrile, dimethylformamide and 1,2,5-trimethylpyrrole. After 30 days, dimethylaminoacetontrile was not detected in the presence of Fenton’s reagent and potassium permanganate, but it’s concentration in samples with sodium nitrite was 77.3 mg/L. In the presence of Fenton’s reagent, potassium permanganate and sodium nitrite after 30 days, N-nitrosodimethylamine concentration decreased by 85, 80 and 50%, respectively. In control sample, N-nitrosodimethylamine concentration decreased by 50%, indicating that sodium nitrite has no effect of on N-nitrosodimethylamine concentration. Only Fenton's reagent allowed to reduce the concentration of 1-methyl-1H-1,2,4-triazole to 50% in 30 days. In the presence of other oxidants, 1-methyl-1H-1,2,4-triazole concentration decreased by 15-20%. As a result of the experiment, Fenton's reagent proved to be the most effective oxidant.