Abstract Thermolytic reverse electrodialysis heat engine (t-RED HE) has been recently proposed as a technology for converting low-temperature waste heat into electricity. The construction and operation of the first world lab-scale prototype unit are reported. The system consists of: (i) a reverse electrodialysis unit where, the concentration gradient between two solutions of thermolytic salts is converted into electricity and (ii) a thermally-driven regeneration unit where low-temperature heat is used to restore the initial conditions of the two feed streams. Regeneration is based on a degradation process of salts into gaseous ammonia and carbon dioxide, which can be removed almost entirely from the exhausted dilute solution by vapour stripping and, subsequently, reabsorbed into the exhausted concentrate solution, thus restoring the initial salinity gradient of the two streams. For the first time, the feasibility of the process was demonstrated through an experimental campaign to evaluate the system performance via long-run tests.