Bimodal mesopores silicas (designated as BMMs) with tailored morphology and controlled structure have been synthesized via varying additive ammonia amount in the TEOS-CTAB-H2O system based on hydrolysis condensation behaviors of silicate species (TEOS) and coefficient principles of cetyltrimethylammonium bromide template (CTAB). The spherical BMMs with an average diameter of 25 -150 rim were prepared in a relative low ammonia concentration solution, while the rod-like BMMs with an average size of 2 pm in length were obtained under a high ammonia concentration aqueous solution. Meanwhile, their corresponding morphologies and textural properties were characterized by various techniques, such as X-ray diffraction, SEM, TEM, FT-IR, TG, and N-2 sorption, and then, the related cooperative mechanism including sol gel chemistry and self-assembly process was put forward. (C) 2013 Elsevier B.V. All rights reserved.