The growth and dissolution of calcium oxalate monohydrate (COM) crystals up to 30 mum in length were investigated in situ by atomic force microscopy. The fast-growing faces grew by the dislocation mechanism, the slow-growing ones (in most cases), by forming 2D-nuclei. The velocity of moving steps at different supersaturations, the normal rates of growth and dissolution of these faces were measured. The dissolution. rate was found to be 3 times higher in the specially prepared Aqua RX water than in distilled water. Adding a small,amount of Al and Fe ions to the water resulted in 5-fold increase of the dissolution rate. Intensive dissolution was observed even when these ions were added to a supersaturated solution. (C) 2003 Elsevier B.V. All rights reserved.