2, 4, 6 trichlorophenol (TCP) is one of the most toxic chlorophenols which is very difficult to biodegradation. Advanced Oxidation Processes (AOPs) is one of the most effective processes for degradation of persistent compounds. Since the mineralization of recalcitrant compound by AOPs often requires long reaction time and strong doses of oxidant, the combination of this process with biological one, is considered as an efficient and economic method. In this work degradation of 2, 4, 6 trichlorophenol in aqueous solution with Fenton reagent (H₂O₂ +Ferrous ion) was studied. The experiment was done in batch mode, and the initial concentration of TCP was 0.60mM. In pH=3, H₂O₂=1.8mM, Fe=0.6mM, more than 99% of TCP was degraded in 10 minutes after the reaction was started. Chloride ion generation as TCP degradation by product was investigated, and it was found that the scavenging effect of chloride is negligible. PH and UV₂₁₅ absorbance analysis, after reaction completion, indicated that generated intermediates had the less chlorinated nature, acidic properties and nonphenolic structure. Chloride ion increases from 0 mg/L to 40 mg/L, pH decreased from 3 to 2.7 and UV₂₁₅ absorbance decreased from 3.2 to 0.6, therefore it can be resulted that their biodegradability modified and their recalcitrance reduced. COD analysis indicated that TCP did not mineralize and in H₂O₂/TCP = 3 and oxidation time of 1 h, COD reduction was only 37%.