In order to compare the humidity standards at the Centre Technique des Industries Aérauliques et Thermiques (France) and the Centre for Metrology and Accreditation (Finland), a dew-point hygrometer was calibrated at both laboratories within a EUROMET project. There were eight measurement points in the range -40 °C to + 60 °C. The difference between the standards was determined and its uncertainty was evaluated. The difference was between -0.03°C and + 0.09°C with the average being 0.01°C. The uncertainty of the difference was ±0.08°C to ±0.17°C (k = 2). The measurements and the analysis of the results are reported in this paper.