The ability of non-living biomass of Penicillium citrinum has been explored for the removal and recovery of uranium from aqueous solutions. The biosorbent was characterized by SEM, EDS and FT-IR. The influences of different experimental parameters such as initial solution pH, initial uranium concentration, contact time, biomass dosage and temperature on adsorption were investigated. The P. citrinum exhibited the highest uranium sorption capacity at an initial pH of 6.0 and at 5 h. Biosorption capacity increased from 103.1 to 127.3 mg g(-1) with an increase in temperature from 298 to 318K at an initial uranium concentration of 50 mu g/mL. Adsorption kinetics was better described by the pseudo-second-order model and adsorption process could be well defined by both the Langmuir and Freundlich isotherms, however, Freundlich isotherm displayed a better fitting model than Langmuir isotherm. The thermodynamic parameters: Delta G degrees (308 K), Delta H degrees, and Delta S degrees for sorption process were determined to be -20.48 kJ mol(-1), 10.76 kJ mol(-1), and 101.43 J mol(-1) K-1, respectively. The results presented in this study showed that the P. citrinum offered great potential as a biosorbent to remove uranium ions from aqueous solutions. (C) 2010 Elsevier B.V. All rights reserved.