Chestnut-like CoFe2O4@SiO2@In2O3 nanocomposite microspheres with hierarchical structures were successfully synthesized by an in situ hydrothermal growth of In2O3 nanowires covering on the CoFe2O4@SiO2 microspheres. The resultant nanocomposite microspheres possessed an average size of 480 nm, while the In2O3 nanowires exhibited a relatively small diameter of 5 nm. Especially, the unique hierarchical structures showed a large pore size of about 18 nm and large specific surface area of 54 m(2) g(-1). The gas sensing results demonstrated that the chestnut-like CoFe2O4@SiO2@In2O3 nanocomposite micro spheres exhibited superior sensitivity and fast response speed to low-ppm-level acetone. That superior property might be attributed to the unique hierarchical structure of chestnut-like CoFe2O4@SiO2@In2O3 nanocomposite microspheres, which could be promising gas-sensing materials. (C) 2017 Published by Elsevier B.V.