Turkey is the world leader in hazelnut production and a large amount of wastes is produced during its harvesting and processing. Obtaining valuable products from hazelnut by-products can add value to those. In this study, xylooligosaccharide (XOS), which has prebiotic potential and not manufactured in Turkey, was selected as the target product. Hazelnut wastes (shell, green leafy cover and pruning wastes) are suitable sources for production of XOS. Although there are some studies on valorization of hazelnut wastes, there is no study about XOS production. In this study, xylan in the shell was hydrolyzed to XOS by autohydrolysis and enzymatic hydrolysis at different conditions. The highest XOS yield was obtained as 62.93% after autohydrolysis at 190 oC for 5 min. The content of XOS with low degree of polymerization (DP<6) increased from 10.13 to 32.74% after hydrolysis with xylanase. XOS from enzymatic hydrolysis was purified by ultrafiltration through 10 and 2 kDa size membranes. The percent of low DP-XOS in liquor was increased after ultrafiltration; however monomers could not be separated. Prebiotic activity and stability of XOS were determined under different conditions. The growth of probiotic bacteria was observed after in vitro fermentation of XOS. XOS showed a good stability to food production and gastrointestinal digestion conditions. The objective of this study was to produce of a high value product such as XOS with prebiotic potential from hazelnut wastes by autohydrolysis and enzymatic hydrolysis. This study was highly original since XOS has been produced from hazelnut wastes for the first time.