A directed study for the undergraduate physical chemistry laboratory for determining the transference number of H[superscript +](aq) using a modified moving boundary method is presented. The laboratory study combines Faraday's laws of electrolysis with mole ratios and the perfect gas equation. The volume of hydrogen gas produced at the cathode is monitored and the perfect gas equation is applied to determine the amount of H[subscript 2](g) produced. The transference number of H[superscript +](aq) is then determined from the volume of HCl(aq) swept by the boundary, the molarity of HCl(aq), and the amount of H[subscript 2](g) produced. The cell is directly powered by 9 V batteries and involves no electronic circuit or a milliammeter. Preparation of the electrochemical cell, experimental procedure, and results of the experiment are presented. (Contains 2 tables and 2 figures.)