Biological treatments to degrade cyanide have shown to be a powerful technology for cyanide removal from industrial wastewaters. It has been previously demonstrated that the alkaliphilic bacterium Pseudomonas pseudoalcaligenes CECT5344 is able to use free cyanide and several metal−cyanide complexes as the sole nitrogen source. The strain CECT5344 has been used for detoxification of the different chemical forms of cyanide that are present in alkaline wastewaters from the electroplating process of the jewelry industry. This liquid residue also contains large concentrations of metals like iron, copper and zinc, making this wastewater even more toxic. A proteomic analysis by LC-MS/MS has been applied to elucidate the molecular mechanisms involved in this bioremediation process in P. pseudoalcaligenes CECT5344. Among others, different proteins related to cyanide and cyanate assimilation, as well as other proteins involved in transport and resistance to metals were induced by the cyanide-containing jewelry residue have been identified.