AbstractThe discovery of superconductivity at 30 K by Bednorz and Muller and 90 K by Wu and Chu, has generated a tremendous activity in the search for higher temperature superconductors. This activity has led recently to the discovery of new compounds with critical temperature as high as 125 K. A general review of the properties of these superconducting oxides will be presented. In particular the attention will be focused on transport critical currents and magnetic field behaviour. The knowledge of these properties is in fact of fundamental importance to evaluate the possibility of large scale applications, as magnetic coils, of this new class of materials.