Procedure to improve the electrical efficiency of the support bars anodes and cathodes in processes of electrowinning of metalsIncludes the steps of: a) one or more cavities machined in a 'V' in the contact area of the support bars, (b) to provide these cavities with an angle of between 10 and 170 degrees,(c) to provide these cavities of a depth between 0.5 and 30 mm, (d) and a separation between 0.5 and 10 mm and a length of between 10 and 300 mm.