An effective fractionation process was sought to produce furfural and cellulose-rich solid from barley straw. Acidified zinc chloride (ZnCl2) was used as a catalyst in order to achieve hemicellulose recovery in the form of liquid hydrolysate. This fractionation process recovered 55.6% of XM (xylan and mannan) in the untreated barley straw under best reaction conditions (10% acidified ZnCl2, 150 ℃, 30 min, and 1/15 of S/L ratio). Hemicellulose hydrolysate was converted into furfural using hydrothermal reaction without additional catalyst. The furfural conversion yield at various reaction temperatures (150, 180, and 210 ℃) was in the range of 59.9-64.5%. The two parameters that affected performance in fractionation processing were reaction temperature and time. Reaction severity (Log R0) was used to evaluate the effects of two processing parameters on hemicellulose recovery. In the ZnCl2 treatment, the data indicated that the proper range of severity was 2.95-3.07 because the XM recovery yield decreased as the reaction condition became more severe beyond that point.