Regenerative cooling using hydrocarbon fuel requires thermal decomposition to increase heat absorption, but a high temperature is required to initiate decomposition and catalysis is expected to enhance decomposition at lower temperature regime. The effects of catalysis on thermal decomposition and coking of normal-dodecane and methyl-cyclo-hexane within a tube heater were experimentally investigated. Platinum (Pt) was spread on the inner surface of a stainless tube, and the inner surface of the tube was heated to target values using an electric heater. Decomposed components were accumulated and analyzed, and heat input was evaluated based on temperature gradient within the stainless tube. The results were compared with those without tube coating to show that the Pt-coating lowered the onset temperature of decomposition by 100 K for both fuels. Additionally, heat absorption per decomposed fuel amount was affected by the Pt-coating and the Pt-coating sizably reduced coking generation.