Pure ZnO and Palladium (Pd)-loaded ZnO nanoparticles containing 0.25, 0.50, 0.75 and 1.0 mol% of Pd were successfully synthesized by flame spray pyrolysis (FSP) and characterized for hydrogen and ethanol sensing applications. The crystalline phase, morphology and size of these nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) in order to correlate physical properties with gas sensing performance. The sensing films were fabricated by coating nanoparticles with organic paste composed of terpineol and ethyl cellulose as a vehicle binder on Al2O3 substrate interdigitated with gold electrodes. The film thicknesses were varied by controlling the numbers of coating. Film morphologies of gas sensors were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Moreover, response time and sensitivity of these sensors towards hydrogen and ethanol were evaluated under operating temperatures ranging from 200 ̶ 350°C in dry air. Finally, The optimum amount of loading Pd and film thickness were investigated.