This document specifies a method for the determination of the chlorine and bromine content of liquid petroleum products, synthetic oils and fluids, and additives for petroleum products (including used oils) that are soluble in organic solvents of negligible or accurately known chlorine/bromine content. The method is applicable to products or additives with chlorine content in the range of a mass fraction of 0,000 5 % to 0,100 0 %, and bromine contents in the range of a mass fraction of 0,001 0 % to 0,100 0 %.