This paper presents how a single rising bubble experiment in the Hallimond Tube can be predicted using computational fluid dynamics model. The study is emphasized on the effect of aspect ratio of cylinder domain to the pressure coefficient and axial velocity around the bubble. A rigid sphere with the radius of 0.00575 m using flow velocity of 0.25 m/s is considered in this study. Numerical and simulated data obtained by other researchers in the similar study were used to validate the simulation results from computational fluid dynamics model. It was observed that a change in width in aspect ratio, causing significant change in the value of simulation data. The highest percentage of difference was observed at the vicinity of θ = 85.26o which is 32.4%.