A novel self-heating hydrogen gas sensor based on zinc oxide nanorods coated on indium fin oxide was fabricated. This sensor utilizes Joule heating effect of indium fin oxide to generate heat, while ZnO acts as a variable resistor to regulate the amount of electric current that passes through indium fin oxide layer upon exposure to oxygen and hydrogen gas. The gas sensor was capable of detecting very low concentration of H-2 in air. Hence, for the first time, a new way of gas detection based on sensor temperature variation as the sensing mode was demonstrated.