The main objective of this work was to study the possibility of improving the biosorption of textile dye basic model, methylene blue (MB) by dead fungal biomass, Aspergillus fumigatus. For an initial concentration of MB (5 mg/L) and under proved optimal conditions (pH 7 and 30 degrees C), the equilibrium was reached after 90 min. A chemical pretreatment of A. fumigatus with NaClO 4 degrees Chl (chlorometric degrees), H2O2 30%, CaCl2 0.1 M, SDS 1 mM, NaOH 0.1 M, NaHCO3 0.1 M: the physical pre-treatment by autoclaving and adding SDS 1 mM, NaCl 1 mM to the MB solutions have allowed a considerable and very significant improvement of MB biosorption. However the chemical pretreatment with a solution of H2SO4 0.1 M, and the addition of PbCl2 0.1 M have lead to lower capacity of biosorption. The maximum biosorption capacity was 125 mg/g. The desorption studies were conducted by changing of the pH value among 3-10. The maximum desorption percentage of MB was found to be 80% at pH 3. The modeling of the experimental data at equilibrium was performed with Langmuir, Freundlich, Langmuir-Freundlich, Dubinin Radushkevich (D-R) and Temkin isotherms. The result has shown that the biosorption was favorable, physicochemical in nature and agree well with Langmuir and Freundlich models, with correlation coefficients close to 1.00 in both cases. (c) 2012 Elsevier B.V. All rights reserved.