The volumetric mass transfer coefficient in a confined plunging liquid jet (CPLJ) bubble column absorber was determined during a steady-state absorption of CO2 in sodium carbonate and bicarbonate solution with an addition of hypochlorite catalyst. Special care was paid while choosing the suitable reaction rate to account for the two different zones in the absorber (mixing zone and pipe flow zone) where the volumetric mass transfer coefficients differ by an order of magnitude. The determined mass transfer coefficients reached 0.6 s(-1) and appeared to be 50% lower than those determined during physical absorption of CO2. Energetic efficiency of the examined CPLJ contactor was also calculated.