Titanium dioxide (TiO2) nanocrystals with specific exposed crystal facet have attracted considerable interest due to their promising applications in the fields of energy and environment. In this paper, we report on a simple solvothermal approach for the synthesis of anatase TiO2 octahedra with high yield, using titanium(IV) sulfate and hydrazine hydrate as the starting materials. The formation mechanism of anatase TiO2 octahedra is suggested. The samples were characterized with XRD, Raman, SEM, TEM, FTIR, XPS, and UV/vis techniques, and further tested as a candidate in photocatalysis to decompose methyl orange in aqueous solution at room temperature. The results show that SO42- ions not only benefit the formation of octahedral nanocrystals, but also inhibit nitrogen doping into TiO2 matrix. More importantly, it is found that the octahedral TiO2 nanocrystals show enhanced photocatalytic activity compared to TiO2 P25 and anatase TiO2 counterparts. (C) 2013 Elsevier Ltd. All rights reserved.