The stiffness of 10 nm diameter cellulose nanowhiskers is reported. These whiskers are produced by acid hydrolysis. These whiskers are dispersed in epoxy resin and placed on the surface of a beam of the same material and deformed in tension and compression using a four-point bending device. By following the molecular deformation of the whiskers using Raman spectroscopy it is shown that, by theoretical models of their dispersion and matrix reinforcement, their stiffness can be derived. The effects of debonding, matrix yielding, and buckling of whiskers are also discussed using this method as a means for studying nanocomposite materials. (C) 2008 American Institute of Physics. ; ISI Document Delivery No.: 330UQ Times Cited: 1 Cited Reference Count: 24 Rusli, Rafeadah Eichhorn, Stephen J.