Lignocelluloses are the most abundant organic materials in the world. These materials are available for biogas production in form of crops, agricultural residuals, forest residuals, and industrial and municipal wastes. Lignocelluloses are principally composed of cellulose, hemicellulose, lignin, extractives and ashes. Cellulose and hemicellulose are the digestible parts of the lignocelluloses and are about 70% of these materials. It means, in theory, it is possible to produce about 300 m3 methane from each ton of lignocelluloses (dry weight). However, the amount of the gas production in practice is much lower than this level. It is mainly due to the recalcitrance structure of lignocelluloses materials. There are several pretreatments methods developing in order to improve the biogas production from lignocellulosic materials. These methods are classified as physical, chemical, thermal and biological pretreatments. These methods have different functions such as reducing crystallinity of cellulose, delignification and removing of hemicellulose, improving enzymatic absorption and desorption etc. In addition, some other challenges such as removing toxic materials or indigestible materials from the wastes could be the target of the pretreatment. Our group at University of Borås is working with these pretreatments since 2005. This presentation will cover the pretreatments methods used and the most interesting results that obtained by the group.