The experimental results on crystal growth of alpha-LiIO3 in space indicated that the critical pH value of alpha-LiIO3 solution, pH,, is increased under microgravity environment as compared with the experimental findings on the earth. For investigating a mechanism of space crystal growth of alpha-LiIO3 and explaining space experimental phenomena, a solid/liquid boundary layer characteristic and solute concentration distribution has been determined by the Mach-Zehnder interferometric technology during crystal growth and dissolution processes of alpha-LiIO3. A fringe carrier technique is introduced to visualize more clearly the boundary layer and solve the concentration distribution. The crystal growth rate of alpha-LiIO3 was measured and calculated. The experimental findings show that the growth rate and the boundary layer characteristics are influenced by natural convection. The concentration distribution along [0 0 0 1] and [0 0 0 (1) over bar] directions are markedly different. The growth rates on the (1 0 (1) over bar(1) over bar) faces are similar to that on (1 0 (1) over bar (1) over bar) faces at pH of 4.06. This finding could be beneficial for understanding the experimental space results on crystal growth. alpha-LiIO3. (C) 2003 Elsevier Science B.V. All rights reserved.