Effect of the naphthalene 2-nitro-4,8-disulfonic acid preparative reduction conditions on the naphthalene 2-amino-4,8-disulfonic acid yield and current efficiency is studied. In particular, the effects of the electrolyte composition, cathode material, current density, temperature, the parent naphthalene 2-nitro-4,8-disulfonic acid concentration are found out. The optimal conditions for the naphthalene 2-amino-4,8-disulfonic acid preparative electrosynthesis in the ammonia-buffer solutions (pH 7.0–8.4) are determined. The naphthalene 2-amino-4,8-disulfonic acid yield and current efficiency of 97.5–98.5% and 65.0–72.2%, respectively, are obtained on scaled-up laboratory unit and pilot plant with a filter-press-type electrolyzer. Based on the experimental data obtained in the scaled-up laboratory unit and pilot plant, the technology of amino-C-acid electrosynthesis is developed. This technology is presented in the experiment-and-industry regulations for the producing of the amino-C-acid and in the requirements specification for designing of a pilot electrolyzer for the current load of 3 kA.