The invention relates to vacuum tubes and especially to electron tubes. To produce the tube, and especially an electron collector comprising several electrodes, the electrodes are produced in the form of blocks of ceramic having a high thermal conductivity. The blocks are electrically conducting (at least on the surface). They are preferably made of an insulating ceramic such as aluminium nitride, and are made conductive over part of their surface. The conductive surface part is preferably formed by a conductive ceramic, preferably based on titanium nitride, or on similar conductive ceramic materials. Thus, increased strength, better heat dissipation and weight reduction are achieved.