To illustrate the principles of the development of a first-of-a-kind process as discussed in an earlier paper on process development strategy and methodology, an account is given of the history of development of the Shell Middle Distillate Synthesis (SMDS) process. Following a discussion of the features of the Fischer-Tropsch synthesis as a basic element of the SMDS process, the rationale behind the combination of the heavy paraffin synthesis step and a selective cracking step for obtaining high yields of middle distillates fuels is explained. Considerations on reactor selection for the heavy paraffin synthesis and the factors which have led to the choice of the multi-tubular trickle-bed reactor for the first commercial SMDS plant are discussed. The role of different process development units and the contributions of different categories of process research and development efforts are placed in the context of the total development programme.