h i g h l i g h t s Porous broom-like CeO 2 was fabricated for the first time by a template-free approach. Based on reaction time and temperature, morphology evolution mechanism has been proposed. Compared with other morphology, reduction property of porous broom-like CeO 2 was enhanced. g r a p h i c a l a b s t r a c t a r t i c l e i n f o a b s t r a c t In this study, CeO 2 with a broom-like porous hierarchical structure was successfully prepared by a simple template-free hydrothermal method. In the whole hydrothermal process, reaction time and temperature play important roles in morphology control. The morphology of the as-prepared samples was character-ized by field emission scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy. Structure information was obtained by using an X-ray diffractometer and Raman analysis. Analyses of elements and chemical valence analysis were carried on X-ray photoelectron spectroscopy. Absorption edge and band gap energy were investigated by UV–vis diffuse reflectance. In addition, the optimum experimental conditions for target products were determined. Compared with various morphology samples' BET data, relative intensity of Raman peaks, catalytic evaluation, we can draw a conclusion that CeO 2 with a broom-like porous hierarchical structure has a higher concentration of oxygen vacancies that results in enhancement of catalytic activity. An Ostwald ripening process with orientative self-assembly was proposed for formation of the broom-like porous hierarchical structure. Ó 2014 Elsevier B.V. All rights reserved.