Environmental implications and the tendency of heavy metals to accumulate in selected tissues of plants and animals, as well as their overall potential to be toxic even at relatively minor levels of exposure, are a source of concern. The use of cheap and effective biological means for heavy metal remediation has been advocated. This study examines the biosorption and bioaccumulation of ferrous ion by Aspergillus terreus (A. terreus) and Trichoderma viride (T. viride) in a batch system. The effects of some important parameters, such as initial metal concentration, temperature and inoculum concentration on biosorption capacity were examined. Langmuir, Freudlinch, Temkin and Dubinin–Radushkevich models were applied to explain the biosorption isotherms of Fe(II) onto the biosorbents. The process fitted well into pseudo first order kinetic model and was best explained by the Langmuir isotherm with maximum absorption capacity of 6.33 and 7.50 mg/g for A. terreus and T. viride, respectively. The calculated thermodynamic parameters (ΔG°, ΔH° and ΔS°) showed that the biosorption of the ferrous ion to the organisms is feasible, spontaneous and exothermic in nature at low temperature.