This method is for determining bromine number and bromine index, by potentiometric titration, in hydrocarbons that are stable at room temperature and have endpoints below 550 C (1022 F) as determined by ASTM Method D 1160 or D 2887. The results denote those compounds that react with bromine under the analytical conditions prescribed in this method, and, in general, are relatable to olefin content. However, certain non-olefinic compounds can constitute a positive interference, while some olefins will not react stoichiometrically (see ASTM D 1159). The olefin content can be estimated using the calculation in ASTM D 1159.