NOVELTY - Producing one or more organic chemical products from a feedstock of macro or microalgae, lipid-containing biomass, or its combination comprises: (a) heating an aqueous slurry comprising the feedstock and water in a pressure vessel at a temperature of about 330 degrees C to about 500 degrees C in the presence of a natural or synthetic clay catalyst or an aluminosilicate catalyst; and (b) separating one or more organic chemical products from the mixture.    USE - The method is useful for producing one or more organic chemical products from feedstock of macro or microalgae, lipid-containing biomass, or its combination; and for manufacturing aromatic compounds at supercritical temperatures. The ethyl benzene or styrene is useful for manufacturing polystyrene of biological origin. The dialkylated or polyalkylated pyrazines are useful for manufacturing by oxidation pyrazine dicarboxylic acids or pyrazine poly carboxylic acids or anhydrides for the precursors of condensation polymers of biological origin (all claimed).    DETAILED DESCRIPTION - Producing one or more organic chemical products from a feedstock of macro or microalgae, lipid-containing biomass, or its combination comprises: (a) heating an aqueous slurry comprising the feedstock and water in a pressure vessel at a temperature of about 330 degrees C to about 500 degrees C in the presence of a natural or synthetic clay catalyst or an aluminosilicate catalyst, preferably a catalyst involving the chemical structures of form ALnSimMpOq, where n, m, p, q are integers and any other than q, including two of them, may have the value of zero, and where M is the sum of additional potential cations, whether or not ionized, to produce a mixture comprising a dispersion of an organic phase and an aqueous phase; and (b) separating one or more organic chemical products from the mixture. An INDEPENDENT CLAIM is an organic chemical product produced by the method selected from pyrazines such as methyl, dimethyl, trtimethyl, ethyl or ethylmethyl pyrazine; hydrocarbons such as toluene, alkenes such as 1-nonene, pentadecene and alkanes such as pentadecane and heptadecane; methylated pyrroles, imides such as N-methyl and N-ethyl succinimide; amides such as hexadecanamide and 9-octadecanamide; lactams such as 2-pyrrolidinone, N-methyl-2-pyrrolidinone, N-ethyl-2-pyrrolidinone, N-butyl-2-pyrrolidinone, 2-piperidinone and caprolactam; crotonaldehyde, saturated and unsaturated aldehydes and ketones such as cyclop entanone, cyclopentenone, methyl cyclopentenones, dimethyl cyclopenetenones, methyl furfural and hydroxymethyl furfural.