Hybrid systems utilizing a zinc-air battery or a Proton Exchange Membrane Fuel Cell (PEMFC) as the high energy density component coupled with a rechargeable battery (lead-acid or nickel-metal hydride) or electrochemical capacitor (EC) bank as the high power density component were tested under a high-pulse application load, Land Warrior (LW). The hybrid power sources successfully operated the LW cyclic load beyond the capabilities of the specific single chemistry systems studied. The zinc-air battery hybrids allowed approximately triple the operation time of PEMFC hybrids. The best performing hybrid system was the zinc-air battery/lead-acid battery. It provided the greatest operating voltage and longest operating time.