AbstractTwo different agricultural wastes, sunflower stalk and tobacco stalk, were evaluated for the production of xylose, which can be used as a raw material and converted to xylitol, a highly valued product. The objective of the study was to determine the effects of H2SO4 concentration, temperature, and reaction time on the production of sugars (xylose, glucose, and arabinose), and on the reaction by-products (furfural and acetic acid) from sunflower stalk and tobacco stalk and to compare the hydrolysis conditions of these wastes. Since both agricultural wastes had different structures, they had different responses to experimental conditions. Response surface methodology (RSM) was used to optimize the hydrolysis process in order to obtain high xylose yield and selectivity. The optimum reaction temperature, reaction time and acid concentration were 120 oC, 30 min and 4% of acid concentration for sunflower stalk and 133 oC, 27 min and 4.9% of acid concentration for tobacco stalk.