Abstract: The invention relates to a process for transforming amino- or hydroxyl-containing materials of plant seed origin into plastics feedstocks, which comprises(a) reacting amino-containing starting materials of plant seed origin with an oxo compound, optionally also with an amino compound, preferably with urea or melamine, simultaneously or subsequently; or(b) reacting hydroxyl-containing starting materials of plant seed origin with an amino compound in an aqueous medium, and optionally reacting the thus-obtained macromolecule with an oxo compound; or(c) reacting hydroxyl-containing starting materials of plant seed origin with an oxo compound in an aqueous medium, optionally reacting the thus-obtained macromolecule with an amino compound,then transforming the obtained macromolecular material into plastics feedstocks in a known way.