The complete conversion of castor oil with 96.0% selectivity toward the hydrodeoxygenation (HDO) product octadecane in 3 h at 250 °C, 40 bars H 2 and 20 bars CO 2 pressure with a high castor oil to catalyst ratio (w/w) of 18.4 was demonstrated using a SiO 2 −TiO 2 -encapsulated one-pot Fe−Au− Pd@SiO 2 −TiO 2 catalyst. This octadecane selectivity was 72.6% higher than what was obtained using a Fe−Ni−Pd@SiO 2 −TiO 2 catalyst under the same reaction conditions, but with only half the castor oil/catalyst ratio as 9.2. At three times the castor oil/catalyst ratio of 27.6, the selectivity toward C 18 using Fe−Au−Pd@SiO 2 − TiO 2 was still 66.8% higher. The one-pot catalysts were also superior to a mesocellular foam-supported Fe−Pd−Ni catalyst synthesized using the conventional two-step wet impregnation method. Pressurized CO 2 in hexane facilitated the HDO pathway obeying Le Chatelier's principle and by lowering the viscosity of the reactant solution. Based on the observed product spectrum, a reaction pathway for the HDO of castor oil over Fe−Au−Pd@ SiO 2 −TiO 2 was proposed. Catalyst characterization revealed different types of active sites in Fe−Au−Pd@SiO 2 −TiO 2 , acting synergistically to catalyze the HDO of castor oil. Single-crystal X-ray diffraction showed that the Fe−Au−Pd ensemble had a tetragonal dipyramidal crystal system with an Au centric nanostructure. Fe−Au−Pd@SiO 2 −TiO 2 possessed impressive H 2 spillover capability driven by the Fe−Au−Pd nanoparticles and a large number of isolated electron-deficient Pd δ+ surface species arising out of Pd−Au interaction via charge transfer. The Fe component of Fe−Au−Pd@SiO 2 −TiO 2 existed as individual Fe, bimetallic Fe−Au/ Fe−Pd, or trimetallic Fe−Au−Pd nanoparticles. The Fe surface of these nanoparticles in its Fe 0 state was the primary HDO site. Due to one-pot synthesis, the catalyst could contain high practical metal loading (96.7% for Fe), resulting in abundant active sites for HDO. Fe−Au−Pd@SiO 2 −TiO 2 was also tested to be stable over at least five cycles.