Abstract: The metrology of the emission of carbon dioxide from liquid fuels require their carbon and hydrogen content. The carbon and hydrogen content of liquid fuel is usually measured via elemental analyzer, and their accuracy require the validation using certified reference materials (CRMs) of pure organic substances for elemental contents. In this study, the CRM of n-decane for carbon and hydrogen content was developed. The content of organic impurities was determined by gas chromatograph with flame ionization detector and differential scanning calorimetry. Karl Fischer coulometric titration and the residue on ignition was used to determine the water content and inorganic impurities content, respectively. The content of the main component was then calculated based on the principle of mass balance. Based on the content of the main component and each impurity, as well as the carbon content of their molecules, the contribution of the carbon content of the component was calculated and then added up to obtain the certified value of the carbon content of the CRM. The certified value of hydrogen content was also calculated by the same method. The certified values are traced to the SI units of mass and temperature of pure substances, as well as atomic weight. The carbon and hydrogen contents of the CRM are 84.411% and 15.585%, respectively. The expanded uncertainty (U, k=2) is 0.003% and 0.003%, respectively, reaching the internationally advanced level. This CRM can be used to validate the accuracy of the carbon content measurement method, ensuring the traceability of the carbon dioxide emissions of liquid fuel.