Pretreating plant biomasses is an important step for effective lignin removal and degradation of cellulose to fermentable sugars. In this study, we optimized pretreatment conditions for peanut shells (Arachis hypogeae ) to obtain the maximum yield of cellulose. For optimization, three parameters were used, i.e., sulfuric acid concentration (0.6%, 0.8%, and 1.0%), substrate loading (5%, 10%, and 15%), and residence time (4 h, 6 h, and 8 h) with and without steam (121EC, 15 psi, 15 min), based on Box-Behnken design of response surface methodology. The results confirmed that the maximum yield of cellulose (71.68%) was obtained under pretreatment conditions of 1% sulfuric acid, 15% substrate loading, and 6 h residence time. The ANOVA results indicated that the proposed model was highly significant having F -value and P -value of 158.63 and 0.000, respectively. Moreover, the efficiency of this pretreatment method was further analyzed using FTIR spectroscopy, indicating structural conformation in the pretreated biomass. The results indicate that the pretreated biomass can be utilized for further processes such as saccharification of lignocellulosic material for bioethanol production.