We report optimization with response surface methodology (RSM) for Pb(II) biosorption conditions from aqueous solutions with powdered natural Polyporus squamosus biosorbent. Brunauer, Emmett and Teller and Fourier transform infrared analyses were performed primarily to determine and investigate the biosorbent surface properties. Central composite design (CCD) in RSM was used to optimize the most important biosorption parameters of pH, initial Pb(II) concentration (C-o, mg L-1), contact time (min) and temperature (degrees C). With the quadratic model equation obtained from CCD, the optimum values were determined as C(o)74.55 mg L-1, pH 5.75, temperature 20 degrees C and contact time 112.6 min. In these conditions, the optimum adsorbed amount of Pb(II) was 13.65 mg Pb(II) per gram of biosorbent and biosorption yield was 89.4%. It was determined that the biosorption kinetic data fitted the pseudo-second-order kinetic equation and biosorption equilibrium data agreed well with the Freundlich isotherm model. Additionally, the thermodynamic parameters showed that biosorption was exothermic. Finally, by performing competitive biosorption from artificial wastewater containing multiple metals, the variation in Pb(II) biosorption capacity of P. squamosus in the presence of different metal ions was investigated.