The reaction of the regioisomeric nitroanilines with KI and HNOs/bentonite system using microwave energy in solvent-free conditions is reported. In accordance with the obtained results, an unusual competence between nucleophilic aromatic substitution versus electrophilic aromatic substitution was detected. With the para isomer two products were obtained, one for each reaction type; however, with the meta-nitroaniline, only the nucleophilic substitution product was detected, and finally with the ortho isomer in addition to the nucleophilic and electrophilic substitution products, we detected the formation of 2,4-diiodonitrobenzene. In order to explain the achieved products, we propose that the last product is formed in two steps: firstly by a nucleophilic aromatic substitution, and secondly by an electrophilic aromatic substitution.