A new and improved laboratory cell has been specifically designed for determination of current efficiency (CE) as a function of isolated variable parameters in the Hall-Heroult aluminium electrolysis process. The anode is designed to give enhanced and reproducible bubble induced electrolyte convection, while the wettable cathode gives a well defined cathode area, and thus a uniform cathodic current density. Results are given of CE and cathode polarization as functions of cathodic current density, and of CE as a function of interpolar distance. Experiments show reproducible and high values of CE, and low and consistent values of cathode polarization. The CE does not vary for interpolar distances between 10 and 40 mm in the present cell. The cell is well suited for experimental determination of CE as function of electrolyte composition, including impurity concentrations, temperature and current density.