The mass transfer parameters of both gas and liquid phases affect the mass transfer flux of CO2 in absorption processes. In this study, an accurate correlation is proposed to calculate the CO2 mass transfer flux in an absorption-reactive process by methyldiethanolamine (MDEA) solution using the Buckingham pi theorem. The various parameters include film parameter, CO2 loading, concentration ratio, partial-to-total pressure ratio, film thickness ratio, and diffusion ratio which are incorporated in the model. An average absolute relative error of 4.4 % for the calculation of mass transfer flux was stated.