In this work, silver/palladium substrates for SERS applications were studied and analyzed. The electroless deposition technique was reviewed and studied step by step; for which the catalyst, activator, precursor and reducing agent were analyzed to modulate the growth of silver nanoparticles and thus obtain a greater number of SERS active sites. The substrates obtained were characterized by X-ray diffraction, atomic force microscopy and scanning electron microscopy. The SERS application of contaminants in alcaline medium was evaluated, as an example arsenic trioxide was used, and it was detected up to 1 ppb.