Gram-positive bacterium Bacillus subtilis biosorbs lead(IV) ion from its aqueous solution. The maximum biosorption of lead is 97.68% (w/w) within 48 h of incubation time with optimum pH 4.5 and optimum temperature 40 degrees C for 700 ppm initial loading of lead in a shake flask (optimum rpm 60). 7 days old and 30% (v/v) of suspension inoculum culture is used in the studies. Lead is measured by using atomic absorption spectrophotometer (AAS) into all air-acetylene flame and absorbance is measured at 283.3 nm. The maximum bacterial growth is noticed as 4.90x 10(8) cells/mL at optimum bioprocess conditions.