Nowadays, the need to replace nonrenewable fuels with renewable fuels such as bioethanol produced from lignocellulose biomass has gained attention. This study aims to convert cornstalk biomass into bioethanol via a biochemical conversion process. In this study, the alkaline (NaOH) pretreatment was used for the delignification process. The effect of particle size, alkaline concentration, and temperature on lignin removal, cellulose recovery, and total reducing sugar recovery was investigated during the study. Response Surface Methodology (RSM) was applied to determine the best combination of the affecting parameters in the alkaline pretreatment. Hydrolysis experiment was conducted for all 20 treated samples to determine reducing sugar by using the dinitrosalicylic acid method (DNS) method in the hydrolysate. The highest lignin removal, cellulose recovery, and total reducing sugar were determined to be 89.56%, 80.42%, and 172.35 mg/g, respectively, at optimized particle size 0.527 mm, an alkaline concentration of 2.602 mol/l, and a temperature of 72.580 °C. The maximum total reducing sugar yield 172.35 mg/g, which is produced from the hydrolysis process was fermented with yeast of a 20% v/v ratio and at room temperature 72 hours. In the end, a bioethanol yield of 29.2 g/L was produced. and also, in FTIR analysis, it was observed that the ethanol produced from corn stalk contains the O-H functional group and C-O groups. Keywords: alkaline pretreatment, total reducing sugar, fermentation, bioethanol, cornstalk