The essential characteristics of two-phase flow are flow pattern, flow pattern maps, void fraction, and pressure gradient. This paper discussed the influence of the pressure gradient on the two-phase flow to know the fluid pressure difference in the pipe. The main problem is that superficial fluid velocity and viscosity affect the pressure gradient significantly. This research was carried out on a glass pipe whose diameter is 1.6 mm with a slope of 5. The condition of the system is not affected by the environment (adiabatic) at room temperature of 27C in a steady state. Materials used in this research are air and, water with a mixture of 40%, 50%, 60%, and 70% Glycerine. Pressure drop was measured with a pressure transducer and resulted in voltage data which are then converted into pressure. The new result was obtained that an increase of superficial velocity increased the pressure gradient, whereas the pressure gradient affected by viscosity was shown in the time-series graph. The pressure gradient on JG = 0.116 m/s, JL = 0.149 m/s and a viscosity of 40% yielded an average pressure gradient of 45.24 kPa/m. Meanwhile, the viscosity of 50%, 60%, and 70%, resulted in the average pressure gradients of 47.59; 47.61; and 47.75 kPa/m respectively. These results indicated that an increase of the viscosity increased the pressure gradient significantly.