Naphthalene (NAP), 1-naphthol (1-NAP) and 2-naphthol (2-NAP) are the thermal decomposition products of naphthalene sulfonates making them potentially new geothermal reservoir permeability tracers, however, to date, no sensitive and fast detection method for these compounds has been developed. In order to facilitate sensitive and rapid analysis of these compounds in geothermal brines and associated steam condensates, a high-performance liquid chromatography (HPLC) method combined with solid-phase extraction (SPE) has been developed.•A method for determination of naphthalene, 1- and 2-naphthol from brines has been developed.•These compounds have been detected in steam samples from three New Zealand geothermal fields.•As breakdown products of NDS/NSA, these compounds have potential use as geothermal tracers.