A new task-based design approach [Menon, A. R., Pande, A. A., Kramer, H. J. M., Grievink, J., & Jansens, P. J. (2007). A task-based synthesis approach toward the design of industrial crystallization process units. Industrial & Engineering Chemistry Research, 46, 3979] is applied to design a crystallization process unit. Task-based design involves the conceptual built-up of a process (unit) from functional building blocks called tasks, which represent fundamental physical events. The motivation for developing this approach is to get a better control over the physical events governing crystalline product quality. To deliver a proof of concept, two lines of research are followed. First of all, several small scale experiments are designed to demonstrate practical feasibility of the approach. The new equipment allows for isolation and manipulation of individual crystallization tasks. Second, a model based on the experimentally tested tasks is developed for a crystallizer design and used in dynamic optimization of three case studies. The results show that completely different and tight product specifications can be achieved with the same design simply by changing the operational policy of the crystallizer. This remarkable increase in flexibility to achieve a broad range of product qualities is the result of the ability to control the rate at which individual crystallization tasks are executed as well as the material flows between those tasks. (C) 2009 Elsevier Ltd. All rights reserved.