This document specifies a method for the determination of the oxygen content in bio-based products using an elemental analyser. The scope is limited to products containing elements C@ H@ O@ N@ Cl@ Br and I without F@ representing at least 95 % of the composition of the product to be analysed. ' NOTE 1 Bio-based materials can contain inorganic components. Oxygen in these inorganic components is not bio-based but will nevertheless contribute to the amount of oxygen determined by the following prescribed methods and therefore influence the results in terms of oxygen content. NOTE 2 Although this document has been drafted for the purpose of the determinations dealing with bio-based content@ it can be also used as a standalone standard for determination of oxygen in organic compounds. NOTE 3 For the purposes of this document@ the term ??% (m/m)?? is used to represent the mass (?? of a material.