The characteristics of gas-liquid flow and mass transfer for absorption of carbon dioxide are experimentally investigated by using a vertical ejector with water jet. The flow patterns in the throat and diffuser are regarded as approximately bubbly flows under the experimental conditions. The gas entrainment rate caused by the vertical flow liquid jet increases with increasing liquid flow rate. The entrainment rate is shown as a function of the liquid flow rate, the geometric shape factor of the nozzle and Froude number. The empirical correlation obtained in this work can predict the entrainment rate within an error of +/-15%. The longitudinal distribution of static pressure in the apparatus is investigated. It is confirmed that the static pressure with gas flow is different from that without gas flow. The longitudinal distributions of the volumetric coefficient of mass transfer in the liquid phase, k(x)a, are investigated. It is found that k(x)a shows a maximum value and increases with increasing molar flow rates of gas and liquid for the single nozzle case.