New experimental data are reported for evaluating the heat-transfer coefficient during condensation of pure vapors, viz Refrigerants 12 and 22, inside a horizontal tube. The test section consisted of three 10 mm I.D. and 12.7 mm. O.D. hard-drawn copper tubes, each 1 m long. Average heat-transfer coefficients for different refrigerant flow rates and temperature differentials were experimentally determined for the three tubes separately. In all, over 235 data points were collected. These data have been used to evaluate three recommended procedures for calculation of the heat-transfer coefficient, viz those of Traviss et al., Azer et al., and Akers and Rosson. The last mentioned correlations have been found to predict the data satisfactorily, whereas the other two have been found unsatisfactory. New correlations of the Akers and Rosson type are suggested that give improved agreement with the data.