Abstract: In this study, we derived the effective mass-transfer coefficient between two-phase flow in a three stratified porous medium, one (water) is flowing and the other (NAPL) is trapped. Traditional volume averaging method was used to calculate the large scale effective properties equation describing NAPL dissolution in one-dimensional stratified systems. One limiting case has been investigated corresponding to local equilibrium dissolution with great mass exchange coefficients. It is interesting to note that this case results in a large-scale non-equilibrium dissolution model. The theoretical developments allow predicting the large-scale effective properties from the Darcy scale characteristics in unit-cell. Darcy scale direct simulations were compared favorably to large-scale predictions obtained from the theoretical models.