Switchgrass is one of the most promising energy crops for production of cellulosic ethanol. The major concern in producing economically feasible cellulosic ethanol is delignification of biomass and optimization of enzyme mix. In this study, pretreatment of Dacotah switchgrass using aqueous ammonia was investigated by applying two different modes of operation: ammonia recycle percolation (ARP), and soaking in aqueous ammonia (SAA). Two alkaline reagents, NaOH and aqueous ammonia, were used for pretreatment of switchgrass. Dacotah switchgrass was found to be recalcitrant even at high temperatures (130⁰C for SAA and 170⁰C for ARP), for further improvement of delignification and retention of hemicelluloses in biomass H₂O₂ and anthraquinone were used along with alkaline reagents. Five different pretreatment schemes were used: aqueous ammonia alone, aqueous ammonia and H₂O₂, aqueous ammonia and anthraquinone, NaOH alone, and NaOH and anthraquinone.  The pretreated samples were subjected to enzymatic digestibility test by using commercial enzymes, like Spezyme CP, Accelerase, Multifect Xylanase and β-Glucosidase using different combinations. The results were analyzed to assess the overall effectiveness of the pretreatment and to determine the optimum enzyme mix.