This perspective article focuses on the recent advances in the rational design of catalyst for NH3 decomposition at different length scales, from catalyst nanoparticles to reactor design. For an overall optimum performance, all scales should be optimized in a concerted manner. The study of the mechanism of reaction has given guidelines for the catalyst design. As far as reactor design is concerned, a structured reactor is beneficial for this reaction because it minimizes the inhibiting effect of produced H-2, besides other inherent advantages. This holistic optimization of catalysts is expected to pave the way for application of NH3 as H-2 storage media.