Hexahydroxy-stannates　(MSn(OH)(6))　are　promising　candidates　for　photocatalytic　degradation　of　highly　stable　aromatic　compounds.　A　series　of　MSn(OH)(6)　(MHS,　M　=　Co,　Cu,　Fe,　Mg,　Mn,　Zn)　was　synthesized　by　a　hydrothermal　method　in　this　work.　The　effects　of　the　hydrothermal　temperature,　time　and　the　solution　pH　on　the　formation　of　MHS　were　investigated.　The　structures,　yields,　optical　properties,　and　morphologies　of　the　products　were　then　studied.　Photocatalytic　degradation　of　gaseous　benzene　(C6H6)　on　the　prepared　MHS　was　investigated　and　compared　with　P25　(TiO2).　The　results　indicate　the　optimal　preparation　condition　of　MHS　is　performing　the　hydrothermal　treatment　at　a　mild　temperature　(90-120　degrees　C)　in　a　weak　base　solution　(pH　10-11).　Only　MgHS　and　ZnHS　exhibit　a　significant　and　stable　activity　for　the　destruction　of　C6H6　and　the　efficiencies　are　substantially　higher　than　that　of　P25.　The　hydroxyl　structure　accounts　for　their　high　performance,　which　facilitates　the　formation　of　the　active　radicals　((OH)-O-.　and　O-2(-.)　and　suppresses　the　deposition　of　the　stable　byproducts.　Due　to　the　restriction　of　the　band　structures,　the　degradation　of　C6H6　cannot　be　achieved　on　the　colored　samples　(M　=　Co,　Cu,　Fe,　and　Mn).　Based　on　the　radicals　analyses　results,　the　degradation　route　of　C6H6　on　and　the　formation　route　of　the　stable　intermediates　on　the　samples　were　finally　proposed.　(C)　2015　Elsevier　B.V.　All　rights　reserved.