The present study showed that the alkali pretreatment of pine wood can significantly improve its biogas yield. The pretreatment resulted in significant reduction in the crystallinity of cellulose and lignin removal, which might be responsible for improved biogas production. However, the efficiency of the treatment highly depends on the time and temperature of the pretreatment. The highest methane yield was achieved after alkali pretreatment with 8% (w/w) NaOH for 10 min at 100 C.