A　series　of　lanthanide　stannate　pyrochlores　Ln2Sn　2O7　(Ln　=　Nd,　Sm,　Eu,　Gd,　Er,　Yb)　nanocrystals　have　been　successfully　synthesized　via　a　facile　hydrothermal　route.　With　the　decrease　of　Ln3+　radius,　the　light　absorption　edge　of　the　as-prepared　Ln　2Sn2O7　shows　a　red　shift　from　Nd3+　to　Yb3+.　Their　photocatalytic　activities　are　found　to　be　improved　with　the　decrease　of　Ln3+　radius.　However,　the　photocatalytic　activity　of　Yb2Sn2O7　is　a　little　lower　than　Er2Sn2O7,　although　the　Yb3+　radius　is　smaller　than　Er3+,　which　may　be　attributed　to　the　full-filled　electronic　configuration　(4f14)　of　surface　Yb2+　intermediates　(formed　by　Yb3+　trapping　a　photo-excited　electron).　The　crystallite　size　and　surface　area　play　the　most　important　role　in　determining　the　activities.　Furthermore,　hydroxyl　radicals　are　detected　to　be　the　major　reactive　species　during　the　photo-degradation　process.　Our　findings　provide　insights　in　the　fabrication　of　highly　efficient　stannate　photocatalysts,　thus　enlarging　the　family　of　photocatalysts　available.　©　2014　Elsevier　Ltd.