An experimental study aims at quantifying the degree of embrittlement imparted to bleached and unbleached cellulose fibers, including newsprint, by a hydrolytic treatment with aqueous solutions of mineral and organic acids. The average particle size after milling one minute in a laboratory ball mill is used as a measure of the embrittlement. The degree of hydrolytic attack is measured by the reduction in the degree of polymerization (DP). A general relationship between particle size and DP was observed; the relationship is influenced to a minor degree by the hydrolytic procedure, type of acid, and type of the cellulosic substrate.