Oscillatory flow reactors (OFR) have been actively developed over the last fifteen years at a number of UK universities, including the department of Chemical Engineering, University of Cambridge. OFRs exploit the uniform and efficient vortex mixing that can be achieved when an oscillatory fluid motion interacts with orifice plate baffles in a tube. One particularly advantageous application area that has been investigated is for performing 'long' (usually over 10 minutes) reactions in configurations which are substantially more compact than batch reactors, and which have substantially smaller length to diameter ratios than conventional tubular reactors. The development of OFRs is at a stage where laboratory and pilot scale feasibility is proven, but where no design methodology exists to implement the OFR on a production scale. In this paper, one such methodology is presented, based on research done over the last four years to develop specific applications for OFRs. The design method is based on a shell-and-tube configuration, whereby a series of standard tube diameters are chosen, and the tube-side steady flow (throughput) and oscillatory mixing conditions are chosen to ensure optimal mixing conditions. The scale-up principle is one of maintaining the same geometric ratios as laboratory scale devices, and ensuring similar values for the oscillatory and net flow Reynolds numbers. Following this protocol should ensure an optimal design, with a near plug flow RTD, efficient heat and mass transfer, effective dispersion (in multi-phase systems) and minimization of power dissipation. Once these criteria have been applied, the reactor is sized on the basis of required residence time, which then fixes the maximum throughput and length for each tube diameter. A choice is then made for the final configuration, based on the throughput requirement, the criteria mentioned above and practical considerations. This method is applied to two industrial case studies, and details are given of feasible designs for full-scale reactors using information front pilot studies already performed.