The solute concentration distribution close to solid/liquid interfaces has been determined by Mach-Zehnder interferometric technology during crystal growth and dissolution processes of NaClO3. A fringe carrier technique was introduced to visualize more clearly the boundary layer and to solve the concentration distribution. Solubility of NaClO3 in aqueous solution from 29.2 to 47.4degreesC was also measured by both an optical interferometer and weight techniques. The experimental results indicate that the boundary layer thickness in the NaClO3 solution depends on the fluid dynamical conditions, the crystal faces and the local position. Large crystals of NaClO3 were grown using seeds, which were nucleated and developed at 50degreesC. Transparent crystals having sizes of more than 34 mm, x 36 mm. x 40 mm were successfully grown by a cooling temperature method. NaClO3 crystals have been chosen as a representative candidate for space experiments in our laboratory. (C) 2002 Published by Elsevier Science B.V.