To achieve a reliable method to calculate the hydrocarbon dew point for natural gases in transmission, samples of natural gas were taken at the inlet of the Magreb-Europe pipeline in Spain. The composition up to the C-12 fraction of each natural gas sample was determined by gas chromatography, and the dew-point curve was measured using a chilled mirror dew-point analyzer. In this work, we present the experimental measurements of dew points for six samples of natural gas between 1.1 x 10(5) Pa and 78.4 x 10(5) Pa in the temperature range from 235.2 to 277.9 K. The experimental results obtained were analyzed in terms of a predictive excess function-equation of state (EF-EOS) method based on the zeroth-approximation of Guggenheim's reticular model. Because the EF-EOS model uses a group contribution model, the availability of every binary experimental data corresponding to every binary interaction in the mixture is not necessary. Considering this and the good results obtained in previous studies, we concluded that the EF-EOS model could be used for proper prediction of the hydrocarbon, water, and water + methanol dew-points of real natural gases, even though binary experimental data for all components of the so-called C-6+ fraction are not available. In this work, the capability of this theoretical model for the prediction of hydrocarbon dew points of the studied samples of natural gas is demonstrated within the studied temperature and pressure ranges. In fact, the model reproduces experimental dew-point temperature data within average absolute deviation between 0.4 and 3.0 K when two components are used for characterizing the composition of each heavy fraction of the samples of natural gas and from 1.6 to 2.3 K when all analyzed components are considered for each fraction.