Discussed are the investigations by which the internal ohmic losses of an ion exchange fuel cell were quantitatively attributed to various cell components. A third method of measuring total cell internal resistance has been evaluated. The method of measuring the catalyst-layer electrode specific electron resistivity has been improved. A mathematical model for calculating total cell resistance based on cell geometry and the specific electron and ionic resistances of the cell components has been set up for computer solution. An experimental program of evaluating contact resistance between the cell and the current collectors has been set up and nearly completed. Investigations of two types of membrane reinforcings in various thicknesses of ion exchange membrane have led to experimental confirmation of a specific thickness of membrane for minimum ionic resistance for a given amount of reinforcing used.