Here we explored the nitration of 4,10-dibenzyl-2,6,8,12-tetraacetylhexaazaisowurtzitane (TADB) and isolated and identified all the nitration intermediates. The substitution of the first acetyl group was found to be a key stage in this process. It is this stage where side destructive reactions of the hexaazaisowurtzitane cage take place actively, reducing the yield of CL-20.