One of the main utilization of bubble columns is for the cultivation of microalgae. Microalgae need carbon dioxide for their growth. The main parameter of bubble column design is the volumetric mass transfer coefficient, kLa. The objective of this study is to determine the kLa of carbon dioxide in an annular bubble column. The kLa of carbon dioxide was formulated from the concentration of dissolved carbon dioxide in water. However, due to the limitation of the measurement of carbon dioxide concentration, the oxygen concentration in water was used. This measurement of oxygen concentration in the annular bubble column was carried out through a dynamic physical method using an oxygen probe. The kLa of carbon dioxide was then formulated from the kLa of oxygen. The effects of the superficial velocity and the water level in the column on the kLa of carbon dioxide were analyzed. The results are that higher superficial velocities and higher water levels yield higher kLa of carbon dioxide. The value of kLa in this study ranges from 0.142 to 0.477 min-1.