The surface tension of naphtha reformate cuts (60-170 degrees C) were predicted using a modified UNIFAC group contribution method. The naphtha was distilled into eleven cuts of 10 degrees C intervals to obtain narrow boiling range cuts. The surface tensions were determined in the temperature range 10-50 degrees C and were compared with predicted values. A standard deviation of 5.9% was found using this method, versus 3.7% when the corresponding states method was used over the temperature range of 60-170 degrees C. However, for the higher temperature range of 140-170 degrees C, this method gave a standard deviation of 2.9% versus 7.6% for the other method.