Proton Magnetic Resonance (PMR) imaging has been used to study the volume-phase-transition in a thermoreversible gel. This is demonstrated in the LCST polymer poly(N-isopropylacrylamide), swollen in water. The volume-phase-transition is conveniently monitored through one-dimensional proton images. PMR images, derived from relaxation and diffusion weighted planar spin-echo experiments, provide insights on the hydration state of water and the motional state of polymer, in the fully swollen and collapsed states of the gel. (C) 2000 Elsevier Science Ltd. All rights reserved.