Effective distribution coefficients for an interface of a binary dilute solid solution (or alloy) growing from its melt are formulated for the steady state using a kink kinetics model. Solutions to the set of equations show that the effective distribution coefficients of energetically different sites in the crystal and the melt will depart from their respective equilibrium values as the degree of dis-equilibrium increases. These results indicate that the compositional change across the interface is gradual or diffuse under both equilibrium and non-equilibrium conditions. The direct exchange of atoms among energetically different sites in the melt adjacent to the interface strongly influences the effective distribution coefficients. The approximate equations of the effective distribution coefficients for an interface are also derived. A diffusion controlled growth model is generalized by incorporating the kink kinetics. (C) 2003 Elsevier B.V. All rights reserved.