Porous alpha-Fe2O3 microflowers, which were composed of many nanospindles assembled by large numbers of nanoparticles, were successfully synthesized by calcining the FeSO4(OH) precursor prepared through a simple ethanol-mediated method. Various techniques were employed to obtain the crystalline and morphological properties of the as-prepared products. The formation process of such microstructure was proposed according to the morphology and component of the products obtained at different reaction time. Moreover, the obtained alpha-Fe2O3 was utilized as sensing materials upon exposure to various test gases. As expected, in virtue of the less-agglomerated configuration and unique porous structure, the hierarchical alpha-Fe2O3 microflowers exhibited higher response as well as faster response/recovery time to acetone when compared with alpha-Fe2O3 nanoparticles. Significantly, the response time was measured to be 1 s at the low operating temperature of 210 degrees C. (C) 2017 Elsevier Inc. All rights reserved.