Adsorption heat-pump and refrigeration systems present many interesting characteristics such as noiseless, non-corrosive and environmentally friendly components; besides, adsorption machines efficiently use heat as primary energy. For these reasons the research activities in this sector are still increasing to solve the crucial points that make these systems not yet ready for the market. In this paper an update of the research trends is presented. The results and the most important recommendations are mainly related to improving the heat transfer inside the machine, to find an economic compromise between mass and heat transfer and to practically realize efficient and cheap regenerative systems.