A successful biogas production process depends upon adequate hydrolysis of macromolecules in the substrate and stable further conversion. The complex and rigid structure of cellulosic, hemicellulosic and lignin chain is preventing lignocellulosic biomass to reach efficient hydrolysis, therefore pretreatment of a substrate is needed for higher biogas and methane yields. There are several different physical and chemical methods of pretreatments available which include the usage of acids, alkalis, organic solvents, ionic detergents, steam, high pressure, grinding, ultrasound, and microwave irradiation. Physico-chemical pretreatments act rapidly on lignocellulose but their upscaling is very expensive in industry. Many studies have been made in finding the best combination of different pretreatment methods and also new biological techniques which could make lignocellulose pretreatment cheaper and environmentally more friendly. Using natural abilities of different fungi, bacteria or yeast to degrade lignocellulose simplifies the whole process. Also cocktails of biotechnologically produced enzymes are effective in degrading lignocellulose.