Effects of an extra PdO layer in resistance-based hydrogen sensors are considered. P-type Si substrates were subjected to porous Si by electrochemical etching at room temperature. One category of samples has PdO layer in its structure while the other one does not. We have used electron-beam method for Pd deposition. Results show that when electron-beam technique is used for Pd deposition, existence of PdO layer will increase the range of sensors' operation up to 1% of hydrogen concentration. These samples will be saturated after 186seconds, while the samples without this layer can detect hydrogen up to 0.6% in 150 seconds response time.