The aim of this work is to extract hemicelluloses polymers from spruce sawdust using High Voltage Electrical Discharges (HVED) pretreatment. HVED pretreatment was carried out in order to improve deconstruction of the wood matrix and to allow easier release of high molecular mass hemicelluloses. The results revealed the advantage of HVED activation step in the process of extraction. The yield of hemicellulose extraction increased with HVED treatment time. In fact, after 4 ms of HVED treatment time in 1 M NaOH solution, the yield obtained was higher as compared to the untreated sample (19 mg/g of dry matter and 15.8 mg/g of dry matter respectively). The molecular weights of extracted hemicelluloses are very high (55 kDa and 47 kDa for 4 ms of HVED-treatment in 1 M NaOH solution and water respectively). The use of different mediums of extraction with HVED pretreatment have revealed a selective solubilization of spruce hemicelluloses.