Considering the critical roles of hydrogen in energy transition and the renewable character of biogas, an integrated process linking ionic liquid (IL) based biogas upgrading and thermal plasma (TP) assisted hydrogen production is conceptually proposed and studied from the process intensification point of view. To select a practically suitable IL absorbent for biogas upgrading, an IL screening is first conducted from an experimental database exhaustively collected from the literature. Following the thermodynamic screening and the assessment of important physical properties, the retained IL is evaluated in the conceptual biogas upgrading process. After that, the upgraded biogas with high biomethane purity is fed into a simulated TP reactor for the production of hydrogen by decarbonisation, where solid carbon could be simultaneously obtained as a second product. The improvement of the combined process is further examined by strategies of heat and power integration. The configuration of the whole integrated process is finally presented, showing a promising scenario for energy efficient and sustainable production of hydrogen.