Enzyme accessibility has been considered as a key factor in the enzymatic conversion of cellulose biomass into biofuel. Cellulase enzyme hydrolysis ability depends to a large extent on the surface area and porosity of cellulose which determines the susceptibility of cellulose to cellulases. Quantifying the porous structure of cellulose is also fundamental to understanding a wide range of binding interactions in the development of cellulose nanocomposites which may contain various chemical and biological additives. The objective of this work was to characterize the surface area and porosity of cellulose nanowhiskers (CNWs) from different acid treatments (H2SO4/HCl) by N2 adsorption technique. The surface area and porosity of CNWs were compared in an attempt to determine how different treatments affect the structure of CNWs. It was observed that CNWs exhibited increased surface area and porosity than unhydrolyzed cellulose. Mesopores existed in the CNWs generated by H2SO4 treatment; and both mesopores and micropores were present in CNWs produced by HCl treatment.