The production of reducing sugar is the most crucial process in the production of cellulosic ethanol and can be divided into two steps. First, pretreatment removes the unwanted constituents of lignocellulose to produce cellulose; then the cellulose is hydrolyzed to glucose (a fermentable sugar) in the hydrolysis step. The study reported on the delignification and fermentable sugar production of coffee husk biomass using microwave-assisted alkaline pretreatment and sequential acid hydrolysis of coffee husk took place. The coffee husk collected from Zege town was prepared and sieved to had appropriate sizes which is necessary for conventional and microwave assisted alkali pretreatment. Compositional analysis was performed for both raw and microwave assisted pretreated coffee husk with NREL and ASTM protocols. Response surface methodology with central composite design was employed to analyze the effect of process variables on delignification. Three independent process variables such as microwave irradiation time (5, 15 and 25 min), particle size (0.5– 0.8, 1.1-1.4 and 1.7-2.4 mm), and alkali concentration (1, 3 and 5% wt/vol) were analyzed. A second-order nonlinear equation was developed to validate the model. Quadratic models were generated and statistical analysis performed to validate the adequacy of the models. The results indicated that the optimal microwave assisted alkali pretreatment condition was 14.841 irradiation time, 1.071mm particle size and 2.898% w/v concentration. Under the optimal condition, maximum delignification yield of 85.864% and fermentable sugar of 141.974 mg/g of raw coffee husk was obtained using microwave-assisted alkali pretreatment method. Compared to conventional biomass heating, higher delignification yield recorded in microwave pretreatment. The application of microwave is an alternative conventional pretreatment method. The present study, therefore, revealed that optimized microwave-assisted alkali pretreatment followed by acid hydrolysis can enhance the yield of fermentable sugars for satisfying the energy need from cellulosic bioethanol. Key words: Coffee Husk, Delignification, Fermentable Sugar, Microwave-Assisted Alkali Pretreatment, Response surface methodology