A new surface-renewal-stretch (SRS) model was developed to correlate experimental data for the time-average overall mass transfer coefficient, K-L,K-av, in liquid-liquid and gas-liquid mass transfer systems. The model is based on the equation of continuity, which includes both turbulent and convective mass transfer at the liquid-liquid and gas-liquid interfaces. The model incorporates Dankwerts surface-renewal model with the penetration theory for surface stretch proposed by Angelo et al. [Angelo, J.B., Lightfoot, EX, Howard, D.W., 1996. Generalization of the penetration theory for surface stretch: application to forming and oscillation drops. A.I.Ch.E. Journal 12 (4) 751-760]. We used our new SRS mass transfer model to correlate successfully the existing interface mass transfer experimental data from published literature. As a result, the experimental mass transfer coefficient data was predicted with a high degree of accuracy. (c) 2006 Elsevier Ltd. All rights reserved.