The transport of corrosion inhibitors in a pipeline carrying crude oil-water mixture has been studied using a transient liquid-liquid two-phase flow model. The fluid flow model (the hydrodynamic model) is based on a two-fluid model of two-phase flow. The model allows simulating the transfer of inhibitor from one phase to another (inhibitor partitioning) under steady-state and transient oil-water flow conditions. Both stratified and dispersed flow patterns can be modeled. Numerical simulations are presented to demonstrate the effects of topography of the line, locations of the inhibitor injection point, flow pattern, and partitioning of the inhibitor between the phases on the distribution of inhibitor concentration along the pipeline. The modeling can be used to predict the inhibitor volume needed to be injected (the dose rate) in order to provide the required inhibitor concentration in critical sections of crude-oil pipelines.