Dynamic simulation is an advanced activity that integrates in the same environment design, operation and control. Compared to steady-state simulation, both modelling and software technology are much more demanding. Concepts for dynamic modelling are introduced by means of an introductory example, such as conservation laws and constitutive equations, extensive and intensive variables, the index problem and process control implementation. This chapter presents how to build a dynamic model and solve it by using generic software, such as Matlab. A separate section considers dynamic modelling of distillation units. The final section is devoted to dynamic flowsheeting, which focus on the entire plant rather than on stand-alone units.