The phase transition behaviour of poly(vinyl alcohol)-graft-N-isopropylacrylamide copolymer membranes has been studied by measuring their steady-state fluorescence spectra and swelling ratios. Crosslinking with glutaraldehyde increased the tensile strength of the copolymer membrane and also resulted in a considerable decrease in the swelling ratio of the membrane. Well defined thermo-control of permeation through the membrane was achieved by crosslinking of the copolymer membrane with glutaraldehyde.