Enhancing　surface　area　is　one　of　the　efficient　ways　to　improve　photochromic　sensitivity　of　WO3　center　dot　0.33H(2)O.　Hierarchical　WO3　center　dot　0.33H(2)O　mesoporous　nanorod　assemblies　were　synthesized　via　proton　exchange　by　adjusting　the　concentration　of　Na2WO4　center　dot　2H(2)O.　When　the　concentration　of　Na2WO4　center　dot　2H(2)O　is　2.0　g　L-1,　mesoporous　nanorods　with　10　similar　to　20　nm　in　diameter　and　an　average　pores　size　of　about　4　nm　were　obtained.　The　novel　WO3　center　dot　0.33H(2)O　porous　structure　possesses　highly　photochromic　sensitivity　and　fatigue　resistance　properties.　It　exhibits　visible-light-driven　photochromic　response　due　to　large　specific　surface　area　originated　from　the　mesoporous　structure.　The　formation　of　mesopores　is　due　to　the　volume　decreasing　in　the　transformation　process　from　WO3　center　dot　H2O　to　WO3　center　dot　0.33H(2)O.　(c)　2012　Elsevier　B.V.　All　rights　reserved.