The degradation of 2,4,6 – trinitrophenol (TNP)in water sample by atmospheric air cold plasma dielectric barrier discharge (DBD) was studied. The DBD reactor consisted of two electrodes separated by an insulating dielectric barrier with the electric discharge voltage varying from 7.0 to 22 kV. The influence of the TNP initial concentration on the degradation initial rate was studied systematically. A series of experiments with varying TNP initial concentrations from 91.02 to 210.17 mg/L was performed to find the initial degradation rate by the air cold plasma dielectric barrier discharge. From these experiments a TNP degradation kinetic equation based on varying the its initial concentration was established being"-R=" ("0.0252" "C" _"TNP" )/("1+0.0076" "C" _"TNP" ). From here it was interesting shown that if 0.0076CTNP << 1 the TNP degradation kinetics obeys the pseudo - first - order reaction, depending on the TNP initial concentrations, such as ln(Ct/C0) = -0.0269t + 0.1605, ln(Ct/C0) = -0.0197t + 0.0792, ln(Ct/C0) = -0.014t + 0.0623 corresponding to the TNP initial concentrations 91.02, 153.3 and 210.17 mg/L respectively. Besides, the influence of TNP initial concentration and electric power on TNP degradation efficiency were determined too.