In this contribution, we present a physically motivated dynamic model for a plasmonic hydrogen sensor based on a multilayer sample design with palladium nanodisks, which exhibits near-perfect absorption at visible wavelengths. This plasmonic gas sensor enables detection of low hydrogen concentrations providing the advantages of optical measurement principles and may be produced cost-effectively as a miniaturizable system. However, the response is highly temperature-dependent and exhibits a nonlinear relationship between the external hydrogen pressure and the output. Furthermore, the response time depends on the hydrogen concentration and it can take up to several minutes until the steady state is reached and the sensor response can be evaluated. By deriving a dynamic model of the sensor behavior, it is possible to compensate these unfavorable properties of the sensing system. The model derived in this paper consists of a model for the pressure-composition isotherms, which describes the relationship between the external hydrogen pressure and the stationary atomic ratio H/Pd in the palladium crystal using thermodynamic relations, a diffusion model with a concentration-dependent diffusion coefficient and a linear model for the optical response. The parameters of the dynamic model are identified based on literature research and measured data. Finally the dynamic model is validated using experimental data at 30°C, 50°C and 90°C.