A non-implantable minimally invasive system (10, 150, 310, 501) for treatment of tissue in a body via direct current ablation comprising: a semi-flexible trans-lumen catheter (14, 44, 714, 720, 146, 152, 300, 200, 400, 503) for insertion into the body wherein a portion of the catheter is to remain outside of the body when the catheter is in a treatment position proximate the tissue to be treated; a power source configured to receive treatment parameters and to apply direct current and power to the plurality of electrodes based on the input parameters; a fixation element (20, 160, 205, 504) operably associated with the catheter for maintaining the catheter in the treatment position during treatment; and between 2 and 12 electrodes (18, 31, 48, 60, 712, 722, 70, 74, 140, 149, 165, 302, 202, 204, 309, 406, 500, 652, 654, 656, 658) having an insulated portion and an active portion; wherein each electrode has a total length of 14 to 22 mm with the active portion having a length of between 3 and 12 mm, wherein the active portion of at least one of the electrodes is suitable for delivering a charge to impart a high pH or a low pH such that a necrotic zone is created; wherein the electrodes are positioned for deployment outwardly from the catheter at an angle of 15 to 90 degrees from a longitudinal axis of the catheter, characterised in that the electrodes are to be deployed through routing holes provided in an outer sheath or sleeve of the catheter; wherein the angles of extension of the electrodes are influenced by the shape and configuration of the routing holes; and in that the power source is configured to apply direct current at a magnitude of between approximately 10 and 50 mA per electrode and at a power of between approximately 20 and 3200 mW of power per electrode to deliver between 15 and 90 coulombs of charge per electrode, such that the ablation of tissue is substantially non-thermal. a semi-flexible trans-lumen catheter (14, 44, 714, 720, 146, 152, 300, 200, 400, 503) for insertion into the body wherein a portion of the catheter is to remain outside of the body when the catheter is in a treatment position proximate the tissue to be treated; a power source configured to receive treatment parameters and to apply direct current and power to the plurality of electrodes based on the input parameters; a fixation element (20, 160, 205, 504) operably associated with the catheter for maintaining the catheter in the treatment position during treatment; and between 2 and 12 electrodes (18, 31, 48, 60, 712, 722, 70, 74, 140, 149, 165, 302, 202, 204, 309, 406, 500, 652, 654, 656, 658) having an insulated portion and an active portion; wherein each electrode has a total length of 14 to 22 mm with the active portion having a length of between 3 and 12 mm, wherein the active portion of at least one of the electrodes is suitable for delivering a charge to impart a high pH or a low pH such that a necrotic zone is created; wherein the electrodes are positioned for deployment outwardly from the catheter at an angle of 15 to 90 degrees from a longitudinal axis of the catheter, characterised in that the electrodes are to be deployed through routing holes provided in an outer sheath or sleeve of the catheter; wherein the angles of extension of the electrodes are influenced by the shape and configuration of the routing holes; and in that the power source is configured to apply direct current at a magnitude of between approximately 10 and 50 mA per electrode and at a power of between approximately 20 and 3200 mW of power per electrode to deliver between 15 and 90 coulombs of charge per electrode, such that the ablation of tissue is substantially non-thermal.