Abundant natural renewable resource, a-pinene, has been transformed into a reaction mixture containing about 60% its dimers and 40% its isomers via dimerization/isomerization over a novel Bronsted-Lewis double acidic heteropoly inorganic-organic salt, Mn-0.5[MIMPS](2)PW12O40. The reaction mixture can be treated as a biomass high energy density fuel with a density of 0.90 g/mL (20 degrees C), a freezing point of 66 degrees C, a viscosity of 26.5 mm(2)/s (similar to 10 degrees C) and a heat value of 39.7 MJ/L The solid catalyst, Mn-0.5[MIMPS](2)PW12O40, has been synthesized via the replacement of protons in neat phosphotungstic acid by both metal cations Mn2+ and organic intermediate 3-(N-methylimidazole) propane sulfonates (MIMPS), and characterized by Fourier-transform infrared and pyridine adsorption Fourier-transform infrared spectroscopy, X-Ray Diffraction, Thermal-gravity Analysis, Brunauer-Emmett-Teller (BET) surface area analysis, Inductively Coupled Plasma Atomic Emission Spectroscopy and potentiometric titration technology. In addition, easy recovery and steady reusability of this catalyst have been demonstrated by an eight-run recycling test. (C) 2018 Elsevier Ltd. All rights reserved.