The technique for preparing step-terraced GaAs surfaces by annealing in the conditions close to equilibrium is further developed. The kinetics of GaAs(0 0 1) surface flattening is experimentally measured. The step-terraced surface morphology formation is characterized by the evolution of root mean square roughness, total length of monatomic steps, and by Fourier and correlation analyses. It is shown that the excess of monatomic step length over the value for the ideal vicinal surface is the most adequate characteristic of the surface smoothing because it decreases inversely proportional with annealing duration. (C) 2012 Elsevier B. V. All rights reserved.