TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The reaction is conducted without a solvent. The high density diesel fuels are generated by blending sesquiterpene mixtures with known cetane enhancers, and blending sesquiterpene fuels with petroleum-based fuels including JP-10, RJ-4, JP-8, JP-5, F-76, Diesel 2, Jet A, and any renewable fuel. Preferred Components: The pure and/or mixed sesquiterpenes are valencene, premnaspirodiene, caryophyllene (all preferred), humulene, clovene, neoclovene, panasinsene, thujopsene, longifolene, cubebene, zizaene, santalene, longipinene, isomers of the above sesquiterpenes and/or other cyclic terpenes. The isomers are alpha -neoclovene or clovene. The hydrogenating catalyst has at least one metal comprising nickel, copper, palladium, platinum, platinum oxide and ruthenium. The heterogeneous acid catalyst comprises Nafion (RTM: Perfluorinated sulfonic acid resins), Amberlyst (RTM: Crosslinked sulfonic acid resins), montmorillonite K-10, zeolites, polyphosphoric acids, cation exchange resins, Lewis acid catalysts, supported Bronsted acid catalysts, and/or mineral acids including sulfuric acid and phosphoric acid. The plant extracts are clove oil and/or any essential oil having significant quantities of cyclic sesquiterpenes. The biomass includes sucrose, glucose, fructose, cellobiose, other reducing sugars, cellulose, or hemicelluloses in any proportion. The high density fuels are pure sesquiterpenes, or prepared by selective fractional distillation of sesquiterpene mixtures (having a density of greater than 0.90 g/ml, net heat of combustion of greater than 137000 btu/gal, and a cetane number of greater than 30). The high density missile/turbine fuels are blends of: cyclic sesquiterpenes with JP-10 in a desired proportion; cyclic sesquiterpenes with jet fuels including JP-5, JP-8 and Jet A; and cyclic sesquiterpenes with petroleum-derived diesel fuel. The high density jet/diesel fuels are blends of cyclic sesquiterpenes with fuels generated by ethylene oligomerization, butene oligomerization or hexene oligomerization. The high density jet/diesel fuels are blends of cyclic sesquiterpenes with diesel fuels produced from natural gas. EXAMPLE - No suitable example given.