This chapter deals with three topics that are relevant to the modern synthetic ammonia industry: the revamping, or retrofittingRetrofitting (revamping), of converters, of inefficient converters using a novel design of internals based on the axial-radial flow of gases; the academic study and improvement of catalysts; and sustainable production of hydrogen. It was the axial-radial-flow concept that created an opportunity for the revival of Ammonia CasaleCatalystsAmmonia Casale. As for catalysts, academic work undertaken in surface physics provided the mechanism for the take up of nitrogen at the surface of the catalyst. There were other important developments, including in China. Finally, there is production of hydrogen, the most costly feature of the manufacture of ammonia, and which is so relevant to the rapidly developing hydrogen economy. Presently the most widely used process is steam reforming of natural gas (methane), but, as with other fossil fuels, this leads to emission of carbon dioxide. In the long term, methods for sustainable and environmentally friendly production of clean, or green, hydrogen by electrolysis of water using renewable energy sources will become necessary.