In the present work, a series of aminocyclotriphosphazene containing sulfur group compounds have been synthesised and characterised by elemental analysis, mass (MS), (1)H and (31)P NMR spectroscopies. The formation of thiophenoxy-substituted aminocyclotriphosphazenes could be explained by different mechanisms based on primary or secondary amino-substituted cyclotriphosphazenes. Compounds 3, 5 and 7 could be formed by a proton abstraction-chloride elimination and 9, 11 and 13 may be constituted both the S(N)(2) and S(N)(1) reaction mechanisms, respectively. These mechanisms are supported by the crystal structures of 5 and 13. Molecular and crystal structures of 5 and 13 have been characterised by X-ray crystallography. The structures of 5 and 13 are monoclinic and have space groups P2(1)/n. (C) 2009 Elsevier Ltd. All rights reserved.