Novel hierarchical urchin-like hollow SnO2 nanostructures with enhanced gas sensing performance. Novel hierarchical urchin-like hollow SnO2 nanostructures have been synthesized via a facile one-pot template-free hydrothermal approach. The size and density of the SnO2 prickles as well as the morphology of the SnO2 spheres can be modified by tuning the synthetic parameters such as temperature, time, concentration, as well as pH value. The novel hierarchical nano-sized SnO2 hollow urchins possess enriched prickles with diameters of 5-20 nm and lengths of < 70 nm and high surface area up to 116 m2 g(-1), exhibiting advanced sensing performance to the ethanol vapor due to the special hierarchical nanostructures and being promising for the potential gas sensor material.