Abstract: Current calibration procedures for hydrocarbon dew point chilled mirror instruments lack traceability. Since cross border transport of natural gas through the grids of various network operators has become general practice, the necessity for the unambiguous determination of hydrocarbon dew point of a natural gas rises. In this paper, it will be shown that the direct relationship exists between hydrocarbon dew point and liquid drop-out content can be used for the calibration of hydrocarbon dew point chilled mirror instruments.For the first time it is now possible to calibrate a hydrocarbon dew point analyser traceable using the ISO 6570 standard. After calibration and adjustment, the measured hydrocarbon dew points of the instrument will correspond to a given potential hydrocarbon liquid content (PHLC) at the same pressure. The calibration method is described in detail in ISO technical report ISO/TR 12148. The results of this work can be considered as the first step in the process towards a harmonized measuring method for the hydrocarbon dew point and thus to improved interoperability at cross border points.