Free convection heat and mass transfer from a vertical surface in a doubly stratified Darcy porous medium subject to Soret and Dufour effects is studied. The similarity solution is possible for the case of constant heat and mass flux conditions, when the thermal and solutal stratification of the medium are assumed to vary in the power function as x1/3. The flow, temperature, and concentration fields are affected by the complex interactions among the diffusivity ratio Le, buoyancy ratio parameter N, Soret number Sr, Dufour number Df, and the thermal and solutal stratification parameters 1 and 2, respectively. The results for the wall temperature and concentration obtained are presented for various values of the parameters Le, N, 1, 2, Sr, and Df. It is noted that large differences between the values of Sr and Df, and of 1 and 2, lead to changes in the sign of the temperature and concentration fields. Copyright © 2007 Begell House, Inc.