The molecular self-diffusion in porous media is hindered by the presence of pore barriers. The observed, or "apparent", diffusivity is less than that which would be determined for the liquid as a bulk fluid. Such phenomenon, called "restricted diffusion", provides information about the local distribution of the fluid phase, and is potentially useful for characterizing the structure of the porous media. This research will develop the experimental methods for measuring self diffusion coefficients in liquids, and apparent diffusivities in porous media. NMR provides a unique method for determining self-diffusion coefficients. In essence, molecules can be "tagged" magnetically, and their movement over time can be observed. The restricted diffusion can be observed by using pulsed field gradient (PFG) NMR in systems of fluids in restricted geometries. PFG NMR restricted diffusion measurements determine apparent diffusivity that can be used as a parameter for pore-size characterization.