The electroreduction of 9-fluoro-10-cyanoanthracene (1) was voltammetrically studied. In contrast to expectations, no halide elimination was observed at the radical anion level but after a radical ion coupling the dimer 9,9 ' -bianthryl-10,10 ' -dicarbonitrile (2) was formed in quantitative yield. The mechanism was studied using digital simulation. Thermodynamic and kinetic parameters were determined. The low activation energy of the dimerization step indicates a diffusion-controlled radical ion coupling, which produces a σ-dimer but not a π-dimer as often suggested in the literature.