[en] This paper presents experimental results on the effect of a surfactant on the flow patterns, pressure drop and heat-transfer coefficients in two-phase, two-component upward flow in a vertical tube. A comparison between the water-air and surfactant solution-air data showed that the surfactant produced very little effect on flow pattern transitions except for the bubble-slug transition. Bubble flow was observed for the surfactant solution-air where slug flow existed for water-air data. The surfactant solution-air frictional pressure drop data were slightly lower than water-air data where differences existed. Slight effects of the surfactant on the heat-transfer coefficients were observed with surfactant solution-air heat-transfer coefficients being lower than the water-air in the region where differences in the flow patterns were observed. The present data were also compared with some correlations to validate their prediction capabilities