NBSP (P-sample), NaIO4 oxidized cellulose (A-sample) and NaIO4-NaCIO2 oxidized cellulose (C-sample) were hydrolyzed by sulfuric acid in heterogeneous and homogeneous systems.Crystallinity Index (CI) was found to be in the order of P>C>A sample and these of the oxidized samples extremely decreased after hydrolysis. In case of the heterogeneous hydrolysis with 4N H2SO4 at 110°C for 24hr, the amount of the residue decreased and the products in the soluble part increased with increasing the functional group content. The product-yields of the oxidized samples were larger than those of the untreated P sample. By hydrolysis of C sample (COOH, 138mmol/100g cell.), glucose (44%), levulinic acid (24%) and formic acid (24%) were produced.In case of the homogeneous hydrolysis with 72% H2SO4 at 23°C for 5hr followed by 1% H2SO4, the yields of glucose, cellobiose and cellotriose decreased with increasing the functional group content. The yields of glucose homologues as for the oxidized samples were smaller than those of P sample. By hydrolysis of A sample (C=O, 203mmol/100g cell.), glucose (19%), cellobiose (10%) and cellotriose (5%) were obtained along with a small amount of glyoxal and erythrose.