This MS thesis designs a control strategy for a hybrid power supply to coordinate a fuel cell and a battery to work together and exploit their advantages and undermine their disadvantages. The aspect of making two power sources work together is to have the fuel cell behave like a current source and have the battery behave like a voltage source. The digital controller designed in this thesis regulates the current output of the DC/DC converter of the fuel cell the achieve current source operation. The battery, the load and the fuel-cell fed converter, are connected in parallel to serve the load.