Rhombic Co 3 O 4 nanorod (NR) array-based gas sensor was successfully fabricated via a facile two-step synthesis approach, including the formation of rhombic Co(OH)F NR arrays as precursor followed by thermal conversion to porous Co 3 O 4 without altering the original shape. Good ohmic contacts with the electrodes and intensive contact with the substrates avoided complicated fabrication process of gas sensors. The NR arrays annealed at 450°C showed high-performance of ethanol detection. The response to 500ppm ethanol gas reached ∼71 and the optimal working temperature was as low as 160°C. Meanwhile, the sensor exhibited good response/recovery kinetics (90s and 60s), outstanding selectivity over several interferential gases and good stability tested in 3 months. In addition, the sensor could detect ethanol at a low detection limit (<10ppm), which exhibited good reproducibility. The high ethanol gas sensing performance of the Co 3 O 4 NRs can be explained by a typical p-type behavior with the one-dimension structure, nano-porosity, large specific surface area, good crystallinity and the open space of nanorod arrays.