The aim of this work is to study the heating efficiency of refractory microstructures by excitation of surface plasmon polaritons in the far infrared that can be used for high temperature applications. We have designed metal grating couplers on molybdenum films to maximize the absorption of a 10.6 μm CO2 laser light source. Molybdenum has been chosen since it is an industrial refractory metal combined with the fact that its optical properties in the far infrared are similar to gold but with stable high temperature performance. Linear gratings have been used as plasmonic couplers on large area substrates produced by laser milling. Real time absolute temperature measurements have been performed showing a 42 % increase in the maximum achievable temperature from 702 K to 985 K.