The rapid preconcentration of lanthanides in aqueous solution is of interest to enable follow-on analysis of nuclear fallout samples. The large negative overpotential of La reduction along with its instability in aqueous solutions has limited electrode-assisted preconcentration efforts to Hg amalgam and carbon paste electrodes. Previous work has shown that lanthanum films can be deposited on the electrochemical quartz crystal microbalance (eQCM). The frequency response of the eQCM tracked the formation of a La film during the cathodic sweep of cyclic voltammograms that resulted in the hydrogen reduction reaction. Recent findings determined that the lanthanum film associated with potentials beyond the cathodic stability limit of water are directly related to the increase in surface pH due to water hydrolysis. Additionally, x-ray photoelectron spectrometry and auger nanoprobe spectrometry results confirm that the films produced in this manner are La(OH)_3. The formation of lanthanum film is likely to follow an electroprecipitation mechanism due to the basic environment on the electrode surface during the hydrogen reduction reaction. Surprisingly, the addition of the ligand α-hydroxyisobutyric acid resulted in films of the form La₂O₃ rather than La(OH)₃. The mechanism of ligand-assisted La₂O₃ formation is being investigated. These findings will aid in miniaturizing the electrochemical preconcentration of lanthanides on microelectrodes.