Abstract: Mass transfer coefficient and axial mixing coefficient in RDC were evaluated from the axial concentration profiles of the continuous phase. Drop size distributions instead of d32 were used in the evaluation of parameters. Axial mixing of the continuous phase and forward mixing of the dispersed phase were considered. Experiments were carried out in a RDC of 76 mm in diameter. Water and n-butanol were used as continuous phase and dispersed phase respectively. Succinic acid as the solute was transferred from water to butanol drops. Mass transfer coefficient kc and axial mixing coefficient Ec were simultaneously determined by matching the calculated concentration profile with the experimental data. The predicted values of kc and Ec with drop size distribution taken into consideration were shown to be lower than those obtained by using d32 only and the estimated Ec will be much higher if the contribution of mass transfer during drop formation was not considered.