In this study, gas-non Newtonian liquid two-phase flows in a horizontal rectangular microchannel have been investigated. The rectangular microchannel has a hydraulic diameter of 0.235 mm, and a width and depth of 0.24 mm and 0.23 mm, respectively. A T-junction-type gas-liquid mixer was used to introduce gas and liquid in the channel. Polyacrylamide aqueous solutions with different mass concentration, which exhibits pseudo plastic with viscoelasticity, were used as non-Newtonian liquids, while the nitrogen gas was used as the test gas. The flow pattern, the bubble length, the liquid slug length, the bubble velocity and frictional pressure drop in two-phase flow were measured. Each experimental data are compared to those for nitrogen gas-water two-phase flow. From the comparison, rheological properties of polyacrylamide solutions are found to significantly affect flow parameters measured. In addition, two-phase frictional pressure drop could be correlated by using Lockhart-Martinelli method with a newly developed two-phase friction multiplier as function of void fraction and rheological flow index. (C) 2015 Elsevier Ltd. All rights reserved.