Polymer gels are well known in the oil industry, but their potential for use as barriers to contaminant transport has not previously received significant study. As a first step, this paper examines the potential for a polyelectrolyte gel to serve as a barrier to the migration of sodium chloride. Two series of tests are reported. These involve the use of hydrogen pulsed field gradient – nuclear magnetic resonance (HPFG–NMR) to measure the self-diffusion on a microscopic scale and the use of magnetic resonance imaging (MRI) to monitor Na¿ and H¿ migration in the polymer gel with time. It is shown that the gel, which has a hydraulic conductivity of 2 × 10¿¹² m/s, has a diffusion coefficient similar to that of compacted clay and greater sorption of Na¿ than is typical for compacted clay.