Highly ordered mesoporous silica SBA-15 platelets have been directly synthesized using triblock copolymer P123 as structure-directing agent and tetraethyl orthosilicate (TEOS) as silica source without additives. By tuning the synthesis temperature and HCl concentration, platelet-like SBA-15 particles with short pore (150-350 nm) running parallel to the thickness of platelets could be facilely obtained. The synthesis temperature and acidity revealed strong effect not only on mesostructural properties, but also on macrostructural morphologies of the obtained materials. It was found that the side to side aggregation of primary particles in an oriented manner occurred and platelet-like particles were formed at the appropriate temperature and acidity. Furthermore, possible mechanism for the growth of SBA-15 platelets was suggested. (C) 2014 Elsevier B.V. All rights reserved.