The removal of Cr(VI) from aqueous solutions by live and pretreated Neurospora crassa fungal biomass was investigated in the batch mode. The influence of solution pH, contact time and initial metal ion concentration as well as pretreatment of biomass on the biosorption efficiency were studied. All pretreatment methods were found to increase the biosorption capacity of biomass in comparison with the live biomass and biosorption capacity of acetic acid pretreated biomass was found to be 15.85 +/- 0.94 mg/g biomass under optimum conditions. The adsorption constants were found from the Freundlich isotherm model at 25 degrees C. The biosorbent was regenerated using 10 mM NaOH solution with up to 95% recovery and reused five times in biosorption-desorption cycles successivelly. The biosorption mechanism of biosorbent was also evaluated by chemical and instrumental analysis including infrared spectroscopy, scanning electron microscopy and X-ray energy dispersion analysis. (c) 2005 Elsevier Ltd. All rights reserved.