Hydrothermal synthesis of octahedron-shaped nanocrystalline zeolite Y in the presence of amphiphilic organosilane surfactant is described. The influence of parameters, such as the surfactant concentration, temperature and reaction time on the structure, size, surface area and porosity of the zeolite Y nanocrystals was systematically investigated. The role of surfactant was bifunctional, contributing towards the preferential crystal growth as well as the mesoporosity in the material. The morphology, structure and composition of the zeolite Y particles were thoroughly characterized by various techniques. Precise tailoring of size of the particles and pores was found to be an artifact of synthesis and processing parameters. A plausible mechanism for the formation and directional growth of octahedron-shaped nanocrystalline zeolite Y is proposed. (C) 2016 Elsevier B.V. All rights reserved.