8944 2022 eng article 0 -- -- -- We introduce a variational structure for the Fourier-Cattaneo (FC) system which is a second-order hyperbolic system. This variational structure is inspired by the large-deviation rate functional for the Kac process which is closely linked to the FC system. Using this variational formulation we introduce appropriate solution concepts for the FC equation and prove an a priori estimate which connects this variational structure to an appropriate Lyapunov function and Fisher information, the so-called FIR inequality. Finally, we use this formulation and estimate to study the diffusive and hyperbolic limits for the FC system. no under review publish Alberto Montefusco Alberto Montefusco Upanshu Sharma Oliver Tse SFB1114-C3 Modeling and Simulation of Complex Processes