Abstract: A process for modifying a polymeric photoactive sulfone membrane includes placing the membrane into the presence of acrylic acid monomer dissolved in a solution and without sensitizer or free radical initiator and exposing the membrane to non-ionizing UV radiation for modifying the membrane by chemical grafting of the monomer at the surface of the membrane. The membrane can be polysulfone, polyethersulfone or polyarylsulfone. The radiation is selected to have an energy below that at which chain scission occurs and above that at which maximum grafting occurs. The process includes washing the modified membrane in a washing agent containing ethanol, glycol, ether, acid, hydrocarbon, or mixtures thereof, to wash homopolymer formed in the solution from the modified membrane, but preferably ethanol.