In the present work, xylan from arecanut husk was extracted using 2 stage alkaline pretreatment process. In first step, biomass was incubated in alkali at different temperatures (25 degrees C, 50 degrees C and 65 degrees C), alkali concentrations (5%, 10%, 15% and 20% w/v), and incubation periods (8 h, 16 h and 24 h) and evaluated for xylan recovery. It was observed that 40-52% of available xylan could be recovered using 10% alkali when incubated for 8-24 h at 65 degrees C. Subsequently, the alkali pretreatment operating conditions which provided good xylan recovery were processed further using hydrothermal treatment to extract more xylan. For maximum xylan recovery (> 90%), best operating conditions were identified when biomass was treated under hydrothermal treatment (1, 1.5 and 2 h) with varying incubation periods (8, 16, 24 h) and alkali concentrations (5%, 10%) using full factorial design. Incubating arecanut husk with 10% w/v NaOH, at 65 degrees C for a period of 8 h, followed by hydrothermal treatment at 121 degrees C for 1 h helped recover > 94% xylan. In the next step, enzymatic hydrolysis process was optimized to recover maximum XOS (Optimized condition: 50 degrees C, pH 4 and 10 U enzyme dose). The hydrolysate comprised of xylobiose: 25.0 +/- 1.2 g/100 g xylan (similar to 71% of XOS), xylotriose: 9.2 +/- 0.65 g/100 g xylan (26.2% of XOS) and xylotetrose: 0.9 +/- 0.04 g/100 g xylan (2% of XOS). The developed process enables to reduce alkali consumption for high recovery of xylan from biomass with relatively higher lignin content for its valorisation into a potential prebiotic oligosaccharide.