The adsorption of ethyl xanthate ion (EX(-)) on a silver electrode in sodium sulphate, phosphate buffer (pH 6.8) and berate buffer (pH 9.2) solutions was studied in situ using Fourier transform IR reflection spectroscopy. The measurements were carried out using a thin-layer flow cell, which allows a continuous supply of the electroactive species into the thin layer. The voltammetric behaviour of the silver electrode in EX(-)-containing solution is characterized by the formation of silver ethyl xanthate (AgEX), which is preceded by a prewave due to chemisorption of ethyl xanthate. An IR band at 1220 cm(-1), assigned to chemisorbed ethyl xanthate, was observed in spectra obtained in the chemisorption region. All IR bands characteristic of AgEX were observed in spectra of a silver electrode surface covered by a few monolayers of AgEX. The in-situ IR measurements also showed that the adsorption of EX(-) starts directly on the positive side of the potential of zero charge of silver (- 0.7 V/SHE).