NOVELTY - A particulate solid biomass material has biomass particles associated with fibers of carbon.    USE - For preparing a bioliquid (claimed) such as fuel.    ADVANTAGE - The solid biomass associated with carbon fibers is more susceptible to conversion to a bioliquid by hydrothermal conversion, enzymatic conversion, mild thermal conversion or catalytic conversion. As a result of the association with carbon fibers the solid biomass material is more susceptible to conversion to bioliquid. The solid biomass materials may be converted to bioliquids in a hydrothermal conversion process at temperatures of less than 300 (preferably less than 240, especially less than 200)degrees C. The ability to operate at lower temperatures entails significant cost savings, because hydrothermal conversion is generally carried out at autogenous pressures. The lower conversion temperatures are associated with significant cost savings as the equipment cost is much lower for reactors designed for the much lower pressures. Biomass particles associated with carbon fibers possess an increased susceptibility to conversion to a bioliquid as compared to unmodified biomass particles of similar composition and size.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) process for preparing the solid biomass material having associated with fibers of carbon, involving either: providing a solid biomass material in particulate form; depositing onto the particulate biomass material particles of a catalytic material capable of catalyzing the formation of carbon fibers, to form an activated biomass; contacting the activated biomass with a suitable carbon source; or mixing solid biomass with carbon nanofibers, and mechanically treating the mixture to embed the carbon nanofibers into the solid biomass; and    (2) process for preparing a bioliquid from a solid biomass material, involving providing the solid biomass in a particulate form; activating the particulate biomass by associating carbon fibers with the biomass; subjecting the activated biomass to hydrothermal conversion at a temperature below 300degrees C, mild thermal conversion, or an enzymatic conversion.