The use of upgraded biogas is considered as one of the most efficient means of utilizing renewable and sustainable energy. Replacing of conventional methods by low-costs, membrane separations is therefore of a great interest. The aim of this project is to develop innovative highly selective membranes with improved performance for efficient biogas upgrading. Two parallel approaches of unique membrane preparation will be used: (i) the supported ionic liquid membranes and (ii) the water-swollen thin film composite membranes. A complementary and multidisciplinary approach to laboratory experiments for gas separation can be provided by modeling, which can pre-select the best ionic liquid and safe a lot of experimental work. The aspect connected with designing, preparation, characterization and evaluation of membranes for efficient biogas upgrading will be addressed to achieve the most successful membrane. The major issues are achieving high selectivity towards the target gas (methane) and testing this new separation method also for other polar gasses.