Abstract: Construction and characterization of a novel long pathlength thin-layer UV-visible spectroelectrochemical cell are reported. The cell utilizes a cylindrical Teflon electrode which is machined to have a 10×2×0.8 mm thin-layer chamber in the lower end, in which a platinum plate working electrode is positioned. As the electrode is plugged into the cell, the walls of the cell close two ends of the thin-layer chamber and serve as optical windows of 10 mm light path-length. A light transparent jacket is provided for temperature controlled experiments. Well behaved thin-layer cyclic voltammograms and spectral responsed for ferrocene redox reaction were obtained in dichloroethane and toluene solutions.