Highly sensitive hydrogen gas sensors were fabricated using a microelectromechanical system (MEMS) and anodic aluminum oxides (AAOs) process. MEMS based gas sensor platform was designed with the multi-layer type for Pd film morphology manipulations. The operating temperature of the micro heater was positively correlated with the heater. Hydrogen sensing response of the sensor showed a good positive linearity as the gas sensitivity increased with increasing hydrogen concentration. The hydrogen sensitivity (defined as ratio of sensor resistances in air and after the hydrogen gas injection) was 0.638% at hydrogen concentration of 2000 ppm. The H-2 sensitivity was very dependent on the thickness and morphology of Pd-nanosized film. The gas sensitivity and response properties showed different behaviors when palladium film was deposited on the anodic aluminum oxide (AAO) layer. The hydrogen sensitivity for the Pd on AAO layer was about 0.783% at the hydrogen concentration of 2000 ppm. The sensitivity of the Pd-AAO layer improved with respect to the pure Pd thin film due to nanoporous nature of AAO. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.