In this work we report the formation of hollow alpha-Fe2O3 (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO3)(3)center dot 9H(2)O and citric acid in water by sol-gel, the precursor was annealed in air at different temperatures between 180 and 600 degrees C. Annealing at 550 and 600 degrees C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250-400 degrees C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow micro spheres is obtained after annealing at 550 and 600 degrees C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented. (C) 2015 Published by Elsevier B.V.