Hierarchical　MoO2　hollow　microspheres　constructed　from　small　solid　spheres　were　successfully　synthesized　by　using　a　simple　route　in　the　presence　of　diethylenetriamine　(DETA),　in　which　solid　spheres　were　composed　of　nanoparticles.　These　synthesized　microspheres　were　characterized　by　XRD,　SEM　and　TEM　measurements.　It　was　found　that　DETA　was　not　only　a　reducing　agent　but　also　a　structure　directing　agent　and　played　a　key　role　in　the　formation　of　this　hierarchical　structure.　Based　on　experimental　results,　a　possible　model　for　the　formation　of　hierarchical　hollow　MoO2　microspheres　was　proposed.　(C)　2012　Elsevier　B.V.　All　rights　reserved.