The backmixing characteristics of the liquid in a countercurrent two-phase how catalytic distillation column was examined. The residence time distribution (RTD) curves were interpreted using the axial dispersion model. The axial Peclet number was obtained by the least-squares fitting method in the entire time domain, and the correlation, Pe(a) = 10.487 ReL-0.224ReG-0.0765, was obtained. An example is given to show the effect of axial dispersion on the yield of Methyl Tert-Butyl Ether (MTBE) synthesized using catalytic distillation.