A facile and versatile polyol mediated solvo-thermal process using zinc acetate has been adopted for the synthesis of mesoporous ZnO nanomaterials having novel morphologies. Polyols used in this study, i.e. ethylene glycol (EG) and polyethylene glycols (PEG) of molecular weight 200 and 400, not only act as solvents but also as structure directing agents. The synthesis using EG leads to the formation of novel square bipyramidal zinc glycolate intermediate, which upon thermal treatment is converted into a nanocrystalline (NC) wurtzite ZnO structure, preserving the square bipyramidal morphology. Zinc glycolate upon hot water treatment (similar to 85 degrees C), results in the formation of NC wurtzite ZnO having a bicone morphology. However, when the synthesis is carried out by replacing EG with PEG-200 or 400, NC wurtzite ZnO having spherical morphologies have been directly isolated. In the case of PEG-200, the NC ZnO spheres displayed radially oriented nanorod features on the surface. A mechanism of formation of these ZnO morphologies is proposed. The synthesized ZnO materials have been used as catalysts for the photodegradation of crystal violet dye under UV-B and UV-C irradiation. The catalytic behavior of the ZnO samples is explained based on their porosity, crystallinity, and microstructure. (C) 2015 Published by Elsevier B.V.