Abstract: A diagnostic method for an electrochemical fuel cell is described wherein a non-steady state polarization curve is obtained. In particular, a current sweep is applied to, for example, a catalyst coated membrane (CCM), membrane electrode assembly (MEA), fuel cell, plurality of fuel cells and the resulting voltage obtained is recorded. At low current densities, the ramp rate may be relatively slow and relatively fast at higher current densities. The ramp rate may increase in discrete steps or continuously throughout the current sweep. A polarization curve of voltage as a function of current may thus be obtained with the entire current sweep lasting less than 20 seconds and more.