In a conventional chemical oxidative polymerization of aniline in poly(sodium 4-styrenesulfonate) aqueous solution, hollow microspheres of polyaniline were easily prepared, instead of common particles. The morphology of the hollow microspheres was studied and confirmed using scanning electron microscopy and transmission electron microscopy. The molecular structure, room temperature conductivities and thermal stability of the resulting polyaniline were characterized using Fourier transform infrared spectroscopy, the standard DC four-probe method, thermogravimetric analysis and differential thermal analysis. The influence of poly(sodium 4-styrenesulfonate) and aniline on the morphology and physical properties of the resulting polymer were investigated. The results showed that the proper ratio of poly(sodium 4-styrenesulfonate) and aniline was a critical factor in the synthesis of hollow microspheres, which may be related to the chemical structure of poly(sodium 4-styrenesulfonate) as polyanion and of polyaniline as polycation and the electrostatic interaction between them in the doping process. A possible formation mechanism is proposed in this work. © 2013 Society of Chemical Industry