This study presents a theoretical investigation of the processes controlling adsorption, capillary condensation and imbibition in nanoporous media. The theoretical model, which is based on the square-gradient classical density functional approach, explicitly includes the relevant interaction forces among fluids and solids in macroscopic porous media. Application of the model to a relative humidity-controlled water uptake experiment in a nanoporous medium is presented to demonstrate the effects of fluid-pore wall interactions on adsorption and condensation-induced imbibition.