Abstract: A procedure is disclosed in the application, for carrying out arc welding under water or in otherwise difficult external conditions. In the procedure, there is introduced in the arc area or in its immediate vicinity, an auxiliary substance having the purpose to boost the ignition of the arc and its burning and to retard the cooling of the weld bead produced, so that the emergence of gases from the welded seam is promoted and the quality of the weld seam improves. The auxiliary substance used consists mainly of soap which is a salt formed by anions of a fatty acid, a fatty acid mixture or a mixture of fatty and resin acids and by metal cations or a mixture of such salts and which may in addition contain water and inorganic salts. Best results have been obtained by using for auxiliary substance soft soaps made of tall oil and which contain salts of both fatty acids, such as oleic and linoleic acid and of resin acids, such as abietic acid.