A new non-invasive visualization technology was successfully developed to determine the hydrodynamics parameters of Taylor flow in monolith channels. With the developed method, the gas and liquid slug lengths as well as the gas holdup in channels of different radial positions were measured. Accordingly, the average gas holdup in different radial zones and the mean slug lengths over the monolith cross-section were calculated with varying superficial gas and liquid velocities. By defining the maldistribution factor, the degree of non-uniform distributions of these parameters over the monolith cross-section was investigated quantitatively. The results showed that a moderate gas-to-liquid velocity ratio can result in uniform distribution for both gas holdup and slug lengths. In addition, the obtained mean slug lengths were well correlated with simplified Qian and Lawal correlations.