We have recently shown that in the classical electrochemical treatment (EChT) of tumors, i.e., the passage of a direct electric current through two electrodes inserted locally in the tumor tissue, from an initial uniform condition two pH fronts evolve, expanding towards each other, inducing extreme pH changes and tumor destruction, mainly by necrosis. Here we extend these results introducing a one-probe two-electrode device (OPTED) containing the cathode and the anode very close to each other (1 mm). Experiments show that upon application of the OPTED-EChT, two half-spherical pH fronts, one basic and the other acid (from cathode and anode, respectively), expand towards the periphery configuring a distorted full sphere. Tracking of the pH front advance reveals a time scaling close to t(1/2), signature of a diffusion-controlled process. An analytic model presented allows the estimation of the time needed for total tumor destruction with a minimum compromise of healthy tissue. Main advantages of the OPTED are the insertion of one applicator rather than two or more (thus minimizing tissue intrusion, for instance, in the nervous system), the ability to reach tumors beyond capabilities of conventional surgery and the minimization of electric current circulation through the treated organ. We propose here this new design which could have significant implications in EChT optimal operative conditions, in particular, in the way in which the evolving pH spherical fronts can cover and destroy a cancer cell spherical casket. (C) 2010 Elsevier Ltd. All rights reserved.