This study aimed to determine the effect of temperature and heating time on the pretreatment of Oil Palm Empty Fruit Bunches (OPEFB). The pretreatment process was carried out to delignify the OPEFB using ionic liquid in the form of 1-Butyl-3-Methylimidazolium Chloride. Analysis of hemicellulose, cellulose and lignin content using the Chesson method. The optimal condition of the delignification …