Distillation remains the most commonly used separation process in the chemical industry. The separation of a homogenous multicomponent mixture into more than two products is usually realized in series of distillation columns, with the amount of energy used in especially these column arrangements being considerable. In that respect, the application of fully thermally coupled distillation columns, such as dividing-wall distillation columns, is a promising alternative to conventional distillation towers. Especially the aspect of getting high value-added products in merely one distillation column with simultaneous savings in both, energy and capital costs, attracts the investors of distillation plants. Furthermore, a growing demand for high-purity products in fine and commodity chemistry within the last years increased the interest of operating dividing-wall columns. Although several theoretical studies have been executed on dividing-wall columns, to the best of our knowledge, an extensive set of experimental data is still missing. In this contribution we present real pilot plant data of a dividing-wall distillation column in combination with simulation results obtained from a mathematical process model. For that purpose a lab scale dividing-wall distillation column has been recently setup in our laboratory. The separation of an industrially relevant multicomponent mixture in products of high purities is examined. Extensive and high quality measurement devices allow for a detailed analysis of the steady state and the unsteady state behaviour. In earlier studies a rigorous process model has been developed, which allows for a detailed analysis of the column startup, whereas startup implies the transition from ambient conditions to the steady state operting point. The model considers several features, which are characteristic for a dividing-wall distillation column, such as the self adjusting vapour split and the heat transfer across the dividing wall. The presentation focuses on the setup of the pilot plant and the experimental data, whereas the profiles of characteristic process variables are analysed and discussed. After introducing the rigorous process model, the simulation results are compared with the pilot plant data for validation purposes. The extensive validation considers the steady state, the dynamic and the startup characteristics of the dividing-wall column. This comprehensive validation is indispensable, as a model-based design of startup strategies demands for a reliable process model. Finally, some results of practically feasible startup strategies will be presented, which enable large savings in startup time. The extensively validated process model is a promising basis for developing time-optimal startup strategies and process control concepts in the near future. Successfully designed control approaches, which are tested by simulation, will be implemented and applied at our pilot plant. These examinations will be the subject of further conference contributions.