Rice straw is a potential source of fermentable sugars for ethanol production. To facilitate saccharification, pretreatment processes must be employed. Preliminary studies performed at the bench scale demonstrated that sodium hydroxide is a promising agent for alkaline pretreatment due to high solubility in water and lower reaction temperatures required, compared to lime pretreatment. A 150-L rotating drum reactor was retrofitted to accommodate steam heating for sodium hydroxide pretreatment of rice straw. Pretreatment conditions included 4kg biomass (dry wt), 6% sodium hydroxide (per g dry biomass), target moisture content of 80% (wet basis) and heating for 6 hours at 70°C. The effectiveness of the pretreatment was assessed by collecting samples at predetermined time intervals and examining changes in biomass composition and enzymatic digestibility. Both glucose conversion ratio and glucose yield (43.89% and 147.7 mg/g raw biomass) from enzymatic saccharification were greater when the pretreatment was performed at a higher temperature of 70°C in the 150-L rotating drum reactor, compared to preliminary studies done at 50^oC in a static system. Glucose yield was increased by 55.2 mg/g raw biomass when comparing samples with 6 hours of pretreatment to untreated rice straw; a 40% increase in glucose conversion ratio was also observed.