The flower-like WO₃structures were successfully synthesized by a simple calcination of W₁₈O₄₉nanowires obtained by a microwave-assisted solvothermal method. The as-prepared products were characterized by field emission scanning electron microscopy, X-ray powder diffraction, transmission electron microscopy, and nitrogen adsorption and desorption measurements. The results indicated that the building blocks of the flower-like structure were intercrossing single crystalline WO₃nanorods with diameter of about 30-40 nm and length of about 300-400 nm. The gas sensing properties of as-prepared products to NO₂and acetone were investigated. It was found that the sensor based on WO₃nanostructures exhibited excellent selectivity and high sensitivity toward NO₂at optimum temperature of 90 degrees C, giving a response of about 42 to 40 ppb NO₂. Significantly, operating at 300 degrees C, the sensor's response and recovery time to 100 ppm acetone was only 1 s and 6 s, respectively.