The scale-up of plasma reactors for bio, chemical, environmental, materials, and energy applications is an active area of research and development [1, 7]. Based upon the successful scale-up of dielectric barrier plasma technology for ozone generation [4] as well as corona discharges for many applications in flue gas treatment (starting with the early work, for example, of Gallimberti [2] and Katsura [3]) the prospects for scale-up for other applications are very promising. We have gathered here a few papers dealing with plasma reactor scale-up by several leading groups. Rabinovich et al. [6] discuss the scale-up of gliding arc reactors, which combine elements of thermal and non-thermal plasma, to 15 kW, for applications in hydrogen generation from syngas from a variety of biological and waste materials, exhaust gas treatment, water treatment, and fuel desulfurization. Professor Okubo and his collaborators [8] have developed a highly efficient and innovative process for SO2/NOx treatment from exhaust gas based on ozone generation by a dielectric barrier discharge reactor (77 kW) and which produces valuable byproducts. The ozone converts NO to NO2 and SO2 reacts with a NaOH solution to generate Na2SO4 which is collected as dry particles and used in glass manufacturing. Dr. Okubo [5] also provides a valuable review describing the overall progress in the scale-up of hybrid systems that combine plasma reactors for removal of NOx and wet-lime gypsum for SO2 removal. The overall message is that the combination of plasma with other process may be the key to developing highly efficient and larger scale industrial applications. While the plan for this special issue included many other possible contributions, the exigencies of the current pandemic may have affected the contributions of others. We remain optimistic that plasma reactors will continue to develop and scale-up issues will be addressed for future applications.