In the present work, nanostructured NiO thin films were prepared from a facile method based on electrophoretic deposition (EPD) using NiOOH sols as the starting material. The scanning electron microscope (SEM) and atomic force microscopy (AFM) observations revealed that the films were comprised of 40-80 nm particles with a thickness of about 100 nm. When using the obtained NiO film as formaldehyde gas sensor, it was found that such kind of nanostructured films have contributed and modified remarkably the sensing properties such as shorter response and recovery time (approximately 10 s and 5 s), higher sensitivity (approximately 3/10 ppm) at lower working temperature (approximately 300 degrees C).