the process comprises : obtainment of n - acetyl - cysteine from l - cystine , by means of the following steps : acetylation of l - cystine to produce n - acetyl - cystine ; electroreduction and desalination by electrodialysis of the n - acetyl - cystine thus produced to give n - acetyl - cysteine ; or obtainment of n - acetyl - cysteine from l - cystine , by means of the following steps : acetylation and desalination of l - cystine to produce n - acetyl - cystine ; electroreduction of n - acetyl - cystine which may or may not come from the preceding step to produce n - acetyl - cysteine ; obtainment of n - acetyl - cysteine from l - cystine by means of the following steps : electroreduction of l - cystine to produce l - cysteine ; acetylation and desalination by electrodialysis of l - cysteine , which may or may not come from the preceding step to produce n - acetyl - cysteine . the n - acetyl - cysteine thus obtained has important uses in the pharmaceutical sector .