Remarkable evidence of anomalous nuclear reactions occurring in condensed matter are observed in electrolysis experiments performed worldwide. Despite the great amount of experimental results coming from the so-called “Cold Nuclear Fusion” research activities, the comprehension of these phenomena still remains unsatisfactory and controversial. On the other hand, as reported by several authors, a common feature of the experiments is the appearance of microcracks on the electrode external surfaces after the experiments. In the present chapter, a macromechanical explanation is proposed, considering a new kind of nuclear reactions, the phono-fissions, which are a consequence of hydrogen embrittlement of the electrodes during the electrolysis. The experimental activity is conducted using a Ni–Fe anode and a Co–Cr cathode immersed in a potassium carbonate aqueous solution. Emissions of neutrons and alpha particles are detected during the experiments and the electrode chemical compositions are analyzed both before and after the electrolysis experiment, revealing the effects of phono-fission reactions occurring in the host lattice of the electrodes. The symmetrical fission of Ni appears to be the most evident process. Such reaction produces two Si atoms, or two Mg atoms, with neutrons and alpha particles as additional fragments.