Heat transfer rates for total condensation inside a single horizontal tube were studied for a range of temperature differences and tube dimensions. Boiling distilled water was used as coolant. Three tube diameters 1/2, 1, 2 inches and four tube lengths, 16, 12, 8, and 4 feet were used, these being regarded as covering the industrial range of condensers. Tube wall, and vapour temperatures inside the test tube were measured at 12 inch intervals along the tube length. Prom these and a knowledge of the heat flux, values of the condensation side heat transfer coefficient were obtained. The results were correlated by the dimensionless equation: [mathematical equation] The mean deviation between calculated and experimental Nusselt number was 0.95%. with a slight sacrifice of accuracy: [mathematical equation] Giving a mean deviation of 3.16% between calculated and experimental value.