It has been shown experimentally that the rest potentials of a commercial iron wire are changed when conducting solutions are made to circulate through a magnetic treatment device that uses a magnetic field. The test solution used magnetically treated 3% NaCl solution and a flow rate of 40, 110 and 220 ml min(-1). The magnetic treatment accelerated or inhibited the dissolution of the iron wire. Most magnetic effects were influenced by the relation between flow rate and magnetic flux density. The effect of the magnetic treatment disappeared after about 3 weeks.