In　this　study,　large　single-crystal　anatase　TiO2　bipyramids　were　first　successfully　synthesized　using　a　simple　hydrothermal　route.　The　synthesized　bipyramids　were　characterized　by　XRD,　SEM　and　TEM　measurements,　and　found　that　these　bipyramids　are　highly　crystalline　anatase　TiO2　with　a　size　up　to　3.6　mu　m　between　the　two　ends.　On　the　other　hand,　it　was　also　found　that　the　size　and　shape　of　bipyramids　were　significantly　influenced　by　the　pH　value.　Based　on　a　series　of　experimental　results,　a　possible　model　for　the　process　of　dissolving-coalescing-growing,　has　been　proposed　for　the　formation　of　large　anatase　TiO2　bipyramids.　(C)　2009　Elsevier　B.V.　All　rights　reserved.