NOVELTY - Thermochemical conversion of biomass material to at least one reaction product comprises: generating thermal energy with at least one heat source (108); providing volume of feedstock; providing volume of supercritical fluid; transferring portion of generated thermal energy to volume of supercritical fluid; transferring at least portion of generated thermal energy from volume of supercritical fluid to volume of feedstock; and performing thermal decomposition process on volume of feedstock with thermal energy transferred from volume of supercritical fluid to volume of feedstock.    USE - The method is useful for thermochemical conversion of biomass material to at least one reaction product (claimed) e.g. bio-oil, char and volatile gases.    ADVANTAGE - The method: provides stabilized reaction products; and removes sugars from the feedstock material at temperatures below 200 degrees C as fructose, sucrose and maltose in which each sugar caramelizes at temperatures below 180 degrees C.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) an apparatus comprising: a thermochemical conversion system (102) including at least one thermochemical reaction chamber (104) for containing a volume of feedstock; and a thermal energy transfer system including a heat transfer element containing a volume of supercritical fluid in thermal communication with at least one heat source, where the thermal energy transfer system is arranged to selectably place the volume of supercritical fluid in thermal communication with at least a portion of the volume of feedstock contained within the thermochemical reaction chamber in order to selectably transfer thermal energy from the heat source to the portion of the volume of feedstock contained within the thermochemical reaction chamber, and the thermochemical reaction chamber is configured to thermochemically convert at least a portion of the feedstock to at least one reaction product with the thermal energy transferred from the supercritical fluid; and    (2) a system (100) comprising: at least one heat source; the thermochemical conversion system; and the thermal energy transfer system.    DESCRIPTION OF DRAWING(S) - The figure shows a block diagram view of a system for performing thermochemical conversion of a carbonaceous feedstock to a reaction product.    System (100)    Thermochemical conversion system (102)    Thermochemical reaction chamber (104)    Carbonaceous material (105)    Heat sources (108)