We report on self-diffusion measurements of all the components in distinct phases of the ternary system water/n-heptane/Igepal CA-520 with pulsed field gradient NMR, The phases are also investigated with electron microscopy, The observed self-diffusion coefficients are discussed in comparison with the structural data obtained from the micrographs, They intimately reflect the effect of the phase state and phase boundaries on the molecular transport in this system.