The cost of raw material has become one of the important considerations in industrial bioprocesses nowadays. A solution to improve the process economy is through the use of lignocellulosic by-products from agricultural sector. Lignocellulosic rice husk is a potential raw material for the production of added-value products due to its high lignocellulose content. Nevertheless, direct utilization of rice husk in the conversion suffers from low product yield. Thus, pretreatment is necessary to break down rice husk recalcitrant structure prior to use. Till date, there is no known pretreatment reagent reported particularly effective in pretreating rice husk. This optimization of pretreatment began with a preliminary study to select a suitable reagent (from 5 acids and 2 alkalis). The best performed reagent was selected for optimization using a three levels/three factors Box-Behnken design and the factors investigated were reagent loading (0.25 – 1.25 %, w/v), pretreatment duration (1 – 3 hour) and temperature (100 – 140°C). From the findings in the selection study, hydrochloric acid (HCl) released the highest total reducing sugars (TRS) into the hydrolysate (15.04 ± 0.63 mg/ml) compared to the others, which released less than 1 mg/ml TRS. Therefore, HCl was chosen as reagent in the optimization pretreatment of rice husk. A quadratic model is chosen for the optimization of pretreatment and the model is significant with insignificant lack of fit. Among the factors investigated, HCl loading and pretreatment temperature were statistically significant at 95% confidence interval, whereas pretreatment duration was found to be insignificant. Hemicellulose and amorphous cellulose in rice husk matrix could be hydrolyzed at high HCl loading and heating temperature even at short duration. Lastly, numerically optimized pretreatment condition was by pretreating rice husk using 0.5% (w/v) HCl loading and heating at 125oC for 1.5 hours. This optimized pretreatment condition would release 22.84 mg/ml TRS.