Abstract: An electromagnetic flowmeter has a flow tube for conducting the fluid or slurry whose flow rate is to be measured, magnetic field coils which are excited by low frequency pulses in use, and two electrodes for detecting the e.m.f. induced across the flowing fluid or slurry by the magnetic field associated with the coils. In order to substantially reduce the noise component of the flow-induced signal, the electrodes are coated with a porous electrically insulating material such as alumina. A considerable improvement in measurement accuracy is thereby obtained.