Helically moving liquid films are principally used in many beat and mass transfer processes, which are usually practiced to minimize longitudinal dispersion, maximize secondary currents and provide compact spacing. In the present work, practical experiments are carried out to determine mass transfer coefficients for thin films of liquid falling in case of straight and coiled tubes. The system used in the present investigation is the absorption Of CO2 into liquid films of distilled water, or ethyl alcohol (96.25%), or ethylene glycol of 12% or 5.2%. The obtained experimental results indicated higher mass transfer coefficient in the helically liquid film. Empirical correlations are concluded by using dimensional analysis method. The correlations relate Sherwood number to the following dimensionless groups for laminar and turbulent regimes. Sh = f (Re-f, Sc, Ga-f) for inclined straight tube Sh = f (De(f), Sc, Ga-f) for helically coiled tube where De(f), Ga-f and Re-f are Dean, Gallileo and Reynolds numbers for flowing films, respectively. While Se and Sh are Schmidt and Sherwood numbers. Crown Copyright (C) 2003 Published by Elsevier Science Ltd. All rights reserved.