Phase is a form of a substance, which can be either solid, liquid, or gas. Multiphase flow is the simultaneous flow of several phases. Two-phase flow is the simplest of multi-phase flow. Two-phase flow is often found both in daily life and in industrial processes, such as in heat exchangers, boilers, nuclear reactors, piping systems, geothermal, natural gas liquefaction, and others. This research was conducted with an experimental method to determine the two-phase flow characteristics, including flow patterns that are formed, maps of flow patterns produced, vacuum fractions, and pressure gradients. The study was conducted in the test section in the form of a glass pipe in diameter of 1.6 mm horizontal position, with the working gas fluid used as air, and a mixture of distilled water and 7% butanol concentration as a liquid working fluid. Value of superficial gas velocity (JG) = 0.025 – 66.3 m/s, and superficial velocity of fluid (JL) = 0.033 – 4.935 m/s. In this study flow patterns are processed using visualization methods with the MOV to AVI program and then processed with virtual dub. The void fraction was calculated using the digital image processing method with the MATLAB R2014a program. The pressure gradient uses the Pressure transducer MPX System fluid pressure sensor that is connected arduino UNO and then connected to software computer.. The result of this study found five formed flow patterns, namely bubbly flow, plug flow, churn flow, slug-annular flow, and annular flow. Based on the formed flow patterns, a flow pattern map is drawn up. The flow pattern map in this study is compared with the existing flow pattern map. From the results of the study it can be seen that the surface tension has an effect on the transition zone of the bubbly-plug. Void fraction results show that at constant JL, as JG increased, gas plug was getting longer, while at constant JG, as JL increased, gas plug was getting shorter; butanol percentage was proportional to void fraction values. Pressure drop results show that generally, as JG and JL. increased, then pressure drop values were getting higher, pressure drop was directly proportional to JG and JL.