Magnesium hydroxide sulfate hydrate (MHSH, 5Mg(OH)(2)center dot MgSO4.3H2O) nanobelts were synthesized under the conditions of ambient pressure and boiling temperature (similar to 101 degrees C). Several sparingly soluble carbonate salts were selected based on the hypothesis that the sparingly soluble carbonate salts in aqueous solution can provide OH- ion in a slow and continual manner, which is important to maintain a low supersaturation environment for one-dimensional MHSH nanobelt growth. The results indicated that the concentration of the reaction ions in the solution is one of the critical parameters for nanobeft growth. Scanning electron microscopy (SEM) showed that the nanobelts are about 50 nanometers in thickness, 200-500 nanometers in width and tens to hundreds of micrometers in length. The higher the solubility product constant of the sparingly soluble salt, the faster the reaction occurred. The effect of temperature on the reaction rate was investigated. The chemistry of the reaction was studied and the mechanism of nanobelt growth was proposed. (C) 2007 Elsevier Inc. All rights reserved.