Comparisons were studied for untreated and pretreated bagasse with dilute alkaline peroxide and steam for bioethanol production by simultaneous saccharification and fermentation (SSF) process in a continuous stirred batch bioreactor using fungi Fusarium oxysporum. The optimum parameters for bioethanol fermentation were: time, 48 h; pH, 6.0; temperature, 50°C; stirring speed, 35 rpm; and bagasse loading, 35 g/L. Maximum concentrations of bioethanol at optimum fermentation process parameters were 18.73 g/L, 19.69 g/L and 20.45 g/L for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. Maximum yields of bioethanol were 0.706 g/g, 0.734 g/g and 0.764 g/g of bagasse at optimum parameters for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. The sp. growth rate (μ) of fungi Fusarium oxysporum was determined at 5.91 s -1, 6.25 s -1 and 7.11 s -1 and maximum sp. growth rate (μ max) was calculated at 11.81 s -1, 12.50 s -1 and 14.22 s -1 for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. The sp. enzyme activity (ν) was found at 138a0 min -1, 1565 min -1 and 1695 min -1 and maximum sp. activity (ν max) was calculated at 2760 min -1, 3130 min -1 and 3390 min -1 for untreated, steam and dilute alkaline peroxide pretreated bagasse, respectively. The first order rate constants (k) were determined as 0.12 h -1, 0.14 h -1 and 0.156 h -1 for untreated, steam and dilute alkaline peroxide pretreated bagasse for fermentation in continuous stirred batch bioreactor, respectively. © 2011 Copyright Indian Institute of Chemical Engineers.