The present work investigated the phase distribution of a gas-liquid flow in five parallel micro-T channels oriented horizontally and examined the flow behavior in header and branch channels, all with trapezoidal cross-section. The hydraulic diameters of the header and the branch channels were 0.611 mm and 0.438 mm, respectively. Pure water and 0.03 wt% SDS aqueous solution were selected as the liquid phase to study the effect of surface tension on gas-liquid flow in parallel micro-T channels. The inlet superficial velocity of gas (nitrogen) and liquid ranges were 0.161-20.080 m/s and 0.017-0.937 m/s, respectively. It was noticed that the added surfactant could facilitate the flow while higher surface tension of pure water led to the blockage of partial branch channels. It was indicated that the distribution characteristics of two-phase in branch channels highly depended on inlet flow patterns. At inlet of slug flow, a significant proportion of gas was rich in the second branch channel at high inlet gas superficial velocity. But when the inlet flow shifted to annular flow, a large amount of liquid flowed into the first and the last branch channels while gas was rich in the middle three channels. For inlet slug-annular flow, the distribution of gas and liquid took on a transitional characteristic. (C) 2012 Elsevier Ltd. All rights reserved.