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In this work, the sorption behavior of two basic dyes, Toluidine blue and Crystal violet (CV), on Esparto grass fibers Stipa tenacissima L., an abundant semi-arid region biomass was investigated. The surface properties of this new adsorbent were analyzed using various techniques such as FT-IR, BET, Differential scanning calorimetric, Boehm titration, and pH(PZC) determination. Batch experiments were carried out to analyze the sorption kinetics and isotherms. The effect of operational parameters such as adsorbent dosage, dye concentration, ionic strength, pH, and temperature onto dye removal was studied. Under optimum conditions (25 degrees C, pH 7.0, contact time of 150min, and 2gL(-1) adsorbent dose), the monolayer sorption capacities were about 40.00mgg(-1) for TB and 43.47mgg(-1) for CV. Equilibrium data were fitted to the Langmuir, Freundlich, and Temkin isotherm equations, and these data were found to be well represented by the Langmuir isotherm. The adsorption kinetics is represented by second-order kinetic model. Evaluated G and H specify the spontaneous and endothermic nature of the adsorption. The adsorption takes place with an increase in entropy (S is positive). FT-IR spectrum was also taken to investigate the functional groups involved in the biosorption of cationic dyes. The obtained results indicated that Stipa tenacissima L. could be used to treat dye containing effluents.