A method for computing the migration rate of planar solid-liquid interfaces in binary alloys has been developed, and is based on the generalised kinetic equation and phase-field technique for crystal growth. The migration rate of the solid-liquid interface is expressed as a function of diffusivity, interfacial energy, temperature, solute concentration, molar volume, free energy and chemical potentials. Each quantity in the expression is either available from handbooks or can be computed using a thermodynamic database. Numerical calculations based on the present theory for the solidification of AI-Si, Al-Cu and Al-Mg binary alloys have been performed. Data fitting by the KGT model, upsilon = ADeltaT(n), reveals that 0.7 < n < 1. The results agree well with prior metallurgical knowledge. (C) 2003 Elsevier Science B.V. All rights reserved.