Abstract Basic investigations show that plasma spraying is a suitable process to produce wear- and corrosion-resistant coatings under water. Underwater plasma spraying (UPS), first carried out at low water depth, offers some advantages over air plasma spraying concerning noise, radiation and dust reduction, as well as in increasing the coating quality, as demonstrated using self-fluxing nickel-based hardsurfacing alloys. The coating quality was investigated by means of microstructure analyses and by measurement of microhardness, porosity and adhesion strength. Owing to the variable environmental conditions the spraying parameters have to be optimized carefully, particularly the spraying distance. In further developments underwater plasma spraying at greater water depths will be dealt with for applications mainly in the offshore industry.