The goal of this project is to demonstrate that enzyme engineering of cellulases can enable the development of consolidated biorefinery unit operations; specifically a consolidation of biomass pretreatment and enzymatic hydrolysis. Our efforts are focused on the development, manipulation, and optimization of novel classes of cellulase enzymes that have been isolated from extremophiles. Extremophiles are organisms that exist in unique environments, such as sulfurous calderons, and possess enzymes that perform optimally in those environments. The majority of industrial cellulase enzymes to date have been derived from bacteria and fungi. Archaea are the third domain of known life and are finding more applications in biotechnology. This is in no small part because most of the archaeal species identified to date have been identified from extreme environments. Environments such as geothermal and deep-sea volcanic sites (80–121 °C), polar regions (-20 °C), acidic solfatara fields (pH < 4) and alkaline springs (pH > 8) and hypersaline lakes (2–5 M NaCl) which were thought to be inhospitable for life have been shown to be teeming with life forms that are unique sources of enzymes with biotechnological importance. Proteins, however, are fragile and easily succumb to extreme environmental conditions that are typically associated with established pretreatment technologies for biomass processing, such as dilute acid. I will present results of our efforts to modify the sequence, structure, and optimal operating characteristics of these enzymes so that a consolidated bioprocessing approach, collapsing the pretreatment and enzymatic hydrolysis steps into one unit operation, can be implemented.