In this article, a low-power hydrogen (H 2 ) gas sensor has been proposed using a two-dimensional (2D) material based Double Gate Field Effect Transistor (2D-FET). It is imperative to highlight that the conventional threedimensional (3D) materials cannot be scaled down to an ultra-low dimension due to the presence of dangling bonds, surface roughness scattering etc. This creates a major challenge in developing low-dimensional sensors for next generation sensing and computing. In this context, we have developed an extensive simulation model, which articulates the physical phenomena behind a catalytic metal gate-based hydrogen gas sensor using a 2D-FET. A 5 nm thin Molybdenum disulfide (MoS 2 ) film has been used as the channel material for the proposed 2D-FET based gas sensor. The sensor has been modelled by emphasizing on the catalytic metal (Palladium) gate approach, where the work function of the gate metal deposited on top of the channel region varies after the absorption of the hydrogen gas. Moreover, the Technology Computer Aided Design (TCAD) based gas sensor model has been developed by considering a change in the pressure of H 2 gas as well. We have also highlighted the effect of Metal/MoS 2 contact on sensor performance. In terms of results, a maximum threshold voltage (V th ) shift of 100 mV has been obtained against a gas pressure of 10 -10 torr, whereas the maximum percentage of change in I ON /I OFF is 100.