During enzymatic hydrolysis, cellulose particles are attacked by cellulases resulting in the production of fermentable sugars. However, prior to the production of significant amounts of fermentable sugars, considerable fragmentation of the initial cellulose particles occurs. Although several investigators have reported on this phenomena, there has been very little effort at assessing the rate and extent of fragmentation, nor have there been analyses of the influence of cellulose structural features and cellulase characteristics on the rate and extent of fragmentation. The purpose of this investigation is to experimentally and mathematically analyze cellulose fragmentation. The influence of mean particles size, cellulosepore volume and crystallinity, and the characteristics of cellulases of Thermomonospora fusca on the rate and extent of fragmentation will be analyzed. Cellulose is the most abundant carbohydrate produced by the biosphere. It is a major component of plant cell walls. In addition, cellulose represents 40 percent of the municipal solid waste generated across the country. Over the last 10 years there has been considerable interest in taping these renewable resources for industrial chemicals and foods. Part of this interest is stimulated by the relatively low cost of cellulosic materials. A number of microorganisms produce enzymes (cellulases) that are capable of converting cellulose to fermentable sugars. Part of this conversion process is the break-up of cellulose particles into smaller particles. This fragmentation process is one of the least understood aspects of enzymatic hydrolysis. The purpose of this investigation is to analyze and to mathematically model the fragmentation process associated with the enzymatic hydrolysis of cellulose. The model to be developed would be useful for assessing the feasibility of using cellulases for the production of dietary fibers and provide more insight into the overall mechanism for producing fermentable sugars.