The objective of this study is the valorization of a sub-product of the fruit of the argan tree; it is the shell of argan nuts which represents about 50% of fresh fruit. It is a natural lino-cellulosic residue that we cou ld turn into charcoal under the effect of chemical activation wi th phosphoric acid which allows the development of a large pore in the activated material. We studied the effect of the activation temperature, activation time and th e amount of acid added to the char yield and the adsorption capacity of the material developed in response to the exper imental determination of the kinetics of adsorption of an o rganic molecule: the methylene blue. The results sh owed that the temperature of 400 °C, the processing time of one h our and the mass ratio (precursor/phosphoric acid) equal to one, are optimal conditions for development of the adsorbent material. The product obtained under thes e conditions has good textural and structural properties; a spec ific surface area S BET reached 1105 m 2 /g and development of surface functions.