Abstract: The present invention is related to an electrode for destruction of biological tissue, suitably tumor tissue such as cancer. Prior art electrodes suffers from several disadvantages, such as e.g. a non-uniform current distribution, resulting in a oval and unpredictable destruction zone in the tissue. The present invention provides an electrode for destruction of biological tissue, comprising an electrical conductor (2) with a first thickness (t.sub.1), provided with electrical insulation (3) having a second thickness (t.sub.2), the conductor being connected to a current source at one end and electrically connected to an electrode head (4) at the other end of the conductor, where the electrode head serves for supplying current to the zone of the biological tissue, wherein the electrode head (4) is substantially spherical (5,10) with a diameter (D), where said diameter of the sphere is equal to or larger than said first thickness (t.sub.1).