A method is presented for preconditioning fuel cell membrane electrode assemblies for use in fuel cell systems which includes exposure to saturated steam at superatmospheric pressures, typically for at least 10 minutes and more typically at least 25 minutes. Typically, the preconditioning method according to the present invention results in reduction of the start up or conditioning time required when the MEA's are first installed in a fuel cell system and improvement of overall performance, as reflected in the achievement of high current density at relatively high voltage. The method may additionally include the step of enclosing the fuel cell membrane electrode assembly in a container which is substantially impervious to water before the fuel cell membrane electrode assembly returns to ambient temperature.