An electromagnetic flowmeter is described which uses electrodes of large area coated with insulating film made of the plastic polymer FEP. The surface impedance of the electrode-liquid interface is both highly uniform and stable: it is free from polarisation impedance and is much less affected by solid deposits than the interfacial impedance of conventional contact electrodes. Consequently, electrodes of large area can be used with good baseline stability. It is also possible to achieve a low noise level. A flowmeter with such electrodes and a quasi-uniform magnetic field represents an approach to the realisation of a stable, efficient electromagnetic flowmeter which is insensitive to the velocity distribution of the flowing liquid. Such instruments could be used for the accurate measurement of flow near bifurcations for the accurate measurement of the flow of liquids having a wide range of conductivity (e.g. >10^-5 S m^-1) and for measuring the flow of corrosive liquids.