In the last few decades, several scientific investigations have described the experimental evidence of non-conventional nuclear phenomena happening in condensed matter during electrolysis, fracture, or cavitation experiments. In spite of the several studies carried out in the area of the so-called “Cold Nuclear Fusion”, the class of these phenomena remains not completely understood. As reported in different papers, the development of cracks on the external surface of the electrodes employed in electrolysis, the chemical composition changes, as well as the subatomic particle emissions during the tests, are evident (Carpinteri et al. in J Condens Matter Nucl Sci 37:68–83, 2023). A mechanical interpretation of the experimental evidence can be based on low-energy phono-fission nuclear reactions, which are a consequence of hydrogen embrittlement, microcracking, and emitted THz phonons (Carpinteri et al. in J Condens Matter Nucl Sci 37:68–83, 2023). In the present chapter, the results of different experiments on Pd and Ni electrodes are discussed under the light of calorimetric and heat generation measurements in correspondence to the neutron emission peaks. The evidence of a positive energy balance is repeatedly confirmed in correspondence to limited time intervals containing the neutron bursts.