Valorisation of olive stone by-product for sugar production using a sequential acid/steam explosion pretreatment

•Olive stone (OS) biomass is evaluated as feedstock for sugar production.•Combined acid hydrolysis and steam explosion successfully fractionates OS.•First acid hydrolysis step recovered 71 % of xylose in raw OS.•Enzymatic hydrolysis of pretreated OS yielded 78 % of glucose.•83 % of sugars in OS were recovered in the whole process.