SUMMARY
The objective of this study is to highlight the reactivity of an aromatic organic acid (gallic acid) dissolved in naturally mineralized water in the presence of chlorine.The experimental tests have revealed significant consumption potentials when sodium hypochlorite is added. The reactivity of these waters is increased by a competition of chlorine reactions with humic organic matter. The evolution of chlorine consumption versus time and the evolution of absorbance UV have identified two steps, a quick step and a slowest step. The observed kinetics are conditioned by the organic and inorganic composition of the tested waters. chlorination mechanisms may correspond to both electrophilic substitution reactions as oxidation.