We evaluated the effect of the chelating reagents in the successive ionic layer adsorption and reaction (SILAR) process by monitoring the formation of one layer of CdS on the S surface of CdS layers prepared by a successive under potential deposition (upd) method. Anodic stripping voltammetry was adopted to measure the amount of CdS deposited on the An substrate. Among the chelating reagents examined, the order of the ability to enhance the deposition by dipping was cysteine > (none) > mercaptoethylamine > triethanolamine much greater than ethylenediamine. Considering the stability constant of the chelatmg reagents to Cd ions, the present experimental result showed that tight binding of Cd atoms to the surface S atoms is an important step in the deposition of CdS by the SILAR method.