Certain aspects of the electrochemical fluorination (ECF) of hexafluorobutanol (HFB) in anhydrous HF (AHF) on Ni electrodes have been examined by mass spectrometry (MS) and X-ray photoelectron spectroscopy (XPS). Measurements were performed using a portable ultrahigh vacuum compatible chamber that allows for the transfer and characterization of specimens without exposure to the ambient atmosphere. Quasi on line MS analysis of the gases released during ECF of HFB/AHF solutions revealed features attributable to perfluorobutyryl fluoride [PBF = CF3CF2CF2C(O)F] with no evidence of the presence of other reaction products. Ex situ XPS analysis of Ni electrodes following ECF yielded spectra consistent with the formation of a rather thick, irregular layer of NiF2 of average thickness of about 150-200 monolayers, with small contributions due to O (6% ) and C (7%) localized primarily in the surface region.