A Sulzer static mixer with SMX internal structure is investigated for its performance with respect to flow behavior, gas hold-up, and mass transfer rates in an air/water system. The reactor consists of 18 such elements arranged in a line with the angle between successive elements being 90 degrees. The void fraction in the reactor is 0.95. The length of the reactor is 90 cm, with an 6.3 cm internal diameter, and is operated cocurrently with vertical up-flow. The fluids used are air and water. In all the experiments performed in the static mixer, water is the continuous phase and air is the dispersed phase. Experiments are conducted with these fluids under laminar flow conditions. With 18 elements in the reactor, Peclet numbers of up to 100 were obtained in laminar flow regime, thus eliminating the parabolic velocity profile (which usually occurs in laminar flow) to a maximum extent. A gas hold-up of 15% was achieved at lower liquid flow rates and higher gas flow rates while mass transfer coefficients of up to 0.037 s(-1) were achieved. Empirical correlations for Peclet number, gas hold-up, and overall mass transfer coefficient as a function of liquid-side and gas-side Reynolds numbers are obtained. From the experimental results, it was observed that a reactor with the Sulzer SMX internal structure would ensure plug flow behavior with enhanced radial mixing in addition to providing superior mass transfer coefficients and gas hold-up. Finally, the higher mass transfer coefficients achieved in the current study are compared to those obtained in a tube filled with Sulzer SMV packing and a dynamic mixer for identical power dissipation conditions.