The processes of degradation of 2,4-dichlorophenol (2,4-DCP) under the action of atmospheric pressure of dielectric barrier discharge (DBD) in oxygen were studied. It was shown that the degradation of 2,4-DCP proceeds efficiently. Degree of decomposition reaches 90%. The degradation kinetics of 2,4-DCP obeys the formal first-order kinetic law on concentration of 2,4-DCP. The effective rate constants depend weakly on the experimental conditions and are equal to similar to 0.2 s(-1). Based on experimental data, the energy efficiency of decomposition of 2,4-DCP was determined. Depending on the conditions, the energy efficiency was in the range of (8-90) x 10(-3) molecules per 100 eV. The composition of the products was studied by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), energy-dispersive X-ray spectroscopy (EDX), attenuated total reflection-fourier transform infrared (ATR-FTIR) spectroscopy, electron spin resonance (ESR) spectroscopy and UV/Visible spectroscopy. It was shown that about similar to 20% of 2,4-DCP is converted to CO2, while the other part forms an organic film on the reactor wall. The substance formed is close to the carboxylic acids in chemical composition and exhibits electrical conductivity and paramagnetic properties. Almost all of the chlorine contained in the 2,4-DCP is released into the gas phase. The active species of the afterglow react with liquid hexane, forming the products of its oxidation. Some assumptions regarding the pathway of the process are discussed.