Lignocellulosic biomass, rich in potential carbon sources and value added products, has been intensively investigated in scope of its costefficient and effective decomposition. Many methods were developed, physicochemical or biological. Nevertheless, they are either expensive, inefficient or pose threat to the environment. Recently discovered proteins, lacking any hydrolytic activity, can be a key to solve problems associated with a slow process of enzymatical, eco-friendly degradation. These proteins belong to three related groups – swollenins, expansins an loosenins. Using different molecular mechanisms, they disrupt hydrogen bonds within cellulose chains, enabling enzymes to perform hydrolysis leading to decomposition of lignocellulosic complex.