Combining Gibbs adsorption equation and McLean's grain boundary segregation model derives an empirical relation for isothermal grain growth. This relation predicts that driving grain boundary energy to zero is possible in alloy with high segregation energy. Then the grain boundary is in a thermodynamic equilibrium in the presence of solute atoms and, therefore, grain growth is stopped. On this basis reducing grain boundary energy through solute segregation inhibits nano-scale grain growth, and then metastable equilibrium can be reached with saturated grain boundaries. Exact values for solute excess of grain boundary available for segregation at saturation, Gamma(b0), Gibbs free energy change of grain boundary segregation pre mole solute, DeltaG(seg) and/or equilibrium grain diameter, D*, can be achieved by fits of this model to the experimental results. (C) 2003 Elsevier B.V. All rights reserved.