A modeling approach based on hydrodynamic analogies is applied to predict the influence of elevated viscosity on the separation efficiency of distillation processes in structured packed columns. An advantage of this approach compared to traditional models based on the film theory is that separation columns can be described without empirical mass transfer coefficient correlations. The separation efficiency was evaluated for two systems with distinct viscosities at different gas and liquid loads and various operating pressures. Simulated concentration profiles and height of a theoretical plate (HETP) values were compared with the data obtained from own experiments. The developed model is capable of correctly predicting the differences in the HETP values of the two evaluated systems. The influence of elevated liquid viscosity on the distillative separation of organic systems in structured packed columns is investigated using a modeling approach based on hydrodynamic analogies. Simulated separation efficiencies are compared to the results of independent experiments at different operating pressures and gas loads for two test systems.