In this study, Lentinus concinnus biomass was immobilized in polyvinyl alcohol/polyethyleneoxide hydrogels (PVA/PEO; referred as composite biomass) and used for removal of Reactive Yellow 86 dye (RY-86) from aqueous solution using free fungal biomass as a control system. The free fungal and composite fungal biomasses were characterized using ATR-FTIR, SEM and analytical methods. FTIR studies of the adsorbent preparations show that carboxylate, hydroxyl and amine groups should be involved in adsorption of the RY-86 dye. The adsorption of RY-86 dye on these adsorbents increased as the initial concentration of RY-86 dye in the medium increased up to 200 mg/l. The maximum RY-86 dye adsorption for the free fungal and composite fungal biomasses, was obtained as 190.2 and 87.6, respectively, using 200 mg/l initial dye concentration, at 25 A degrees C, and at pH 5.0 with 2.0 h contact. The equilibrium data were well described with the Freundlich and Temkin isotherm models. The adsorption of RY-86 dye was fitted best by the pseudo second-order kinetic model. Thermodynamic parameters (Delta GA degrees, Delta HA degrees, and Delta SA degrees) showed that RY-86 dye adsorption on both adsorbents were spontaneous process.