Although multiphase transportation of petroleum fluids commonly occurs in the field, investigations of wax deposition, have been limited in the:case of single-phase oil flow for the past few decades. The main,complication for wax deposition research in multiphase flow is the variety of flow regimes and one has to analyze the transport characteristics in each flow regime. In the area of water-in-oil dispersed phase flow, previous studies provide limited information on the effects of water droplets on the-mass transfer of wax. This study discusses, the increase in the wax diffusion path to reach the pipe wall caused by the water droplets. The impact of the water droplets on wax molecular diffusion in water-in-oil dispersions is quantified using NMR diffusometry. Two commonly used empirical approaches for wax diffusivity calculation in single phase flow have been evaluated for water-in-oil dispersed flow and neither provides consistent predictions compared to experimental measurements. Finally, a fundamental approach for the calculation of effective wax diffusivity in water-in-oil dispersion is proposed and verified.