To yield stable base resistance and reproducible sensing characteristics, thin film based sensors are considered superior than particulate Taguchi type sensor. The sensing characteristics of ferrite based thin film sensor have hardly been reported in literature. In the present work, the hydrogen sensing characteristics of magnesium zinc ferrite thin film sensor is reported by varying the film thickness, test gas concentration and sensor operating temperature. These thin films were deposited on alumina substrate by sol gel spin coating route. X-ray diffraction analyses and electron microscopy images of the thin film confirm the nano-crystalline nature of these films. It is reported that the film thickness plays a major role to control the gas sensing characteristics of the deposited films. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.