NOVELTY - Forming fuel blend comprising higher hydrocarbons involves contacting biomass feedstock having cellulose/water with organic solvent having partial miscibility with water to form digested biomass stream (S1); contacting (S1) with molecular hydrogen in presence of molecular hydrogen activating metal catalyst under organic phase hydrothermal condition to form hydrocatalytically treated mixture (M1); phase separating (M1) into organic hydrocarbon-rich phase and water phase having water soluble oxygenated hydrocarbon; and processing portion of water phase and/or organic hydrocarbon-rich phase.    USE - For forming a fuel blend comprising higher hydrocarbons, preferably fuel additive, gasoline fuel, diesel fuel, or jet fuel (claimed).    ADVANTAGE - Use of an organic hydrocarbon-rich solvent improves the solubilization of hydrogen into the reaction mixture relative to that which can be obtained with an aqueous phase solvent. It also allows for convenient recycle of the organic solvent phase via liquid-liquid separation and decant, following biomass digestion and reaction. Because biomass is most economically fed to a biofuels process as a wetted or only partially dried feedstock, and because water is formed upon catalytic addition of hydrogen to biomass and biomass-derived intermediates, physical separation of excess water and organic hydrocarbon-rich solvent after the digestion and reaction step, is a process advantage in requiring less energy and equipment, relative to the use of thermal distillation to separate solvents from water in a aqueous solvent-based process. The process is therefore more energy efficient and more effective in hydrocatalytic processing, including hydrogenation, hydrodeoxygenation and hydrogenolysis of biomass-derived intermediates, than a comparable process conducted in the presence of a fully water miscible, aqueous solvent mixture.    DETAILED DESCRIPTION - Forming a fuel blend comprising higher hydrocarbons involves: (a) providing a biomass feedstock containing cellulose and water; (b) contacting the biomass feedstock with an organic solvent having partial miscibility with water at 25 degrees C, to form a digested biomass stream containing the organic solvent and water, where the mass ratio of an organic solvent to water is greater than 1:1; (c) contacting the digested biomass stream with molecular hydrogen in the presence of a molecular hydrogen activating metal catalyst, under organic phase hydrothermal conditions to form a hydrocatalytically treated mixture that contains several hydrocarbon molecules and oxygenated hydrocarbon molecules; (d) phase separating the hydrocatalytically treated mixture, by liquid-liquid separation, into an organic hydrocarbon-rich phase and a water phase comprising water soluble oxygenated hydrocarbons; (e) providing at least a portion of the organic hydrocarbon-rich phase to step (b) to form at least a portion of the organic solvent; and (f) processing at least a portion of the water phase and/or at least a portion of the organic hydrocarbon-rich phase, to form a fuel blend comprising higher hydrocarbons.