Transformation of Moo3nanobelts into Moo3 nanofibers with high surface defect has been achieved by the application of pulsed temperature during hydrothermal growth. Moo3nanobelts and nanofibers are characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and surface area analysis by nitrogen adsorption-desorption technique. Results clearly revealed that high crystalline, lower thickness, high surface area, and high surface defects are present in the Moo3 nanofibers as compare to Moo3 nanobelts. Furthermore, ethanol sensing properties of these M003 nanobelts and Moo3 nanofibers were examined, where Moo3 nanofibers show superior ethanol sensing properties due to the above mention advantages in Moo3 nanofibers.