Adsorption phenomena and surface-derived reactions on interfaces are fundamentally important processes in environmental chemistry, energy, catalysis or materials processing, and play a crucial role in the control of membrane performance. Adsorption of species at the surface of membrane materials has been a vast topic of investigation for decades, with both fundamental impact and direct spin-off in industry. In this minireview, the pivotal role of adsorption for both gas-and liquid-phase membrane separations is underlined with a focus on inorganic and composite membrane materials, their design strategies, transport mechanisms and associated performance. A particular attention is dedicated to fouling phenomena and emerging surface treatment methods. Finally the role of adsorption for membrane microstructure characterisation and defect detection is discussed.