The potential of pennywort(Hydrocotyle vulgaris)for phytoremediation of C.I.Acid Blue 92(AB92)was evaluated.The efects of various experimental parameters including pH,temperature,dye concentration and plant weight on dye removal efciency were investigated.The results showed that the optimal condition for dye removal were pH 3.5 and temperature 25°C.Moreover,the absolute dye removal enhanced with increase in the initial dye concentration and plant weight.Pennywort showed the same removal efciency in repeated experiments(four runs)as that obtained from the first run(a 6-day period).Therefore,the ability of the plant in consecutive removal of AB92 confirmed the biodegradation process.Accordingly,a number of produced intermediate compounds were identified.The efect of treatment on photosynthesis and antioxidant defense system including superoxide dismutase,peroxidase and catalase in plant roots and leaves were evaluated.The results revealed a reduction in photosynthetic pigments content under dye treatments.Antioxidant enzyme responses showed marked variations with respect to the plant organ and dye concentration in the liquid medium.Overall,the increase in antioxidant enzyme activity under AB92 stress in the roots was much higher than that in the leaves.Nevertheless,no significant increase in malondialdehyde content was detected in roots or leaves,implying that the high efciency of antioxidant system in the elimination of reactive oxygen species.Based on these results,pennywort was founded to be a capable species for phytoremediation of AB92-contaminated water,may be efective for phytoremediation dye-contaminated polluted aquatic ecosystems. The potential of pennywort (Hydrocotyle vulgaris) for phytoremediation of CIAcid Blue 92 (AB92) was evaluated. The efects of various experimental parameters including pH, temperature, dye concentration and plant weight on dye removal efciency were investigated. The results showed that the optimal condition for dye removal were pH 3.5 and temperature 25 ° C. Moreover, the absolute dye removal enhanced with increase in the initial dye concentration and plant weight. Pennywort showed the same removal efciency repeated test (four runs) as that obtained from the first run (a 6-day period). Before, the ability of the plant in consecutive removal of AB92 confirmed the biodegradation process. Accredited, a number of produced intermediate compounds were identified. The efect of treatment on photosynthesis and antioxidant defense system including superoxide dismutase , peroxidase and catalase in plant roots and leaves were evaluated. The results revealed a reduction in photosynthetic pigments content u nder dye treatments. Antioxidant enzyme reactions showed marked variations with respect to the plant organ and dye concentration in the liquid medium. Overall, the increase in antioxidant enzyme activity under AB92 stress in the roots was much higher than that in the leaves. significant increase in malondialdehyde content was detected in roots or leaves, implying that the high efciency of antioxidant system in the elimination of reactive oxygen species. Based on these results, pennywort was founded to be a capable species for phytoremediation of AB92-contaminated water, may be efective for phytoremediation dye-contaminated polluted aquatic ecosystems.