In recent years, substantial steps into the transition toward a bio-based economy have been taken. Therefore, biomass, due to its physical and chemical properties, has become one of the key sources to produce bio-based value products. From the current point of view, cellulose is the most common organic biopolymer and is considered as a source of the raw material for environmentally friendly and biocompatible products. The aim of this study was to analyze the effect of hydrolysis time (30–70 min) and temperature (160–180 ºC) at different amounts of aluminum sulfate octadecahydrate as catalyst (0 %, 5 %and 7 % of the oven-dried material) on the content of cellulose in the hemp shives leftover after furfural production. The results have shown that it is possible to save up to 83 % of initial cellulose in the hemp shives leftover if the produced yield of furfural is similar to the industrial scale production yield, which is 55 % from the theoretically possible one. The highest loss of cellulose in hemp shives was observed after hydrolysis at 180 ºC, 7 % catalyst of the oven-dried mass and 70 min, whereas a smaller loss of cellulose was observed under autohydrolysis conditions. Thus, the study identifies important structural features of the lignocellulosic leftover and relevant hydrolysis parameters related to the commercialization of lignocellulosic biorefineries.