Proton Exchange Membrane fuel cell (PEMFC) is considered as a primary source of electrical energy for the DC-DC boost power converter. System's PEMFC/DC-DC boost power converter zero dynamics are analyzed and appeared to be stable. Relative degree approach is applied for direct control of the output load voltage and the fuel cell current in the presence of the model uncertainties. The sliding mode observer is employed for identification of the load resistance, which estimated value is used for generating the fuel cell current command profile. The decoupled traditional SMC and 2-SMC super-twisting sliding mode controller are designed to control the output voltage the PEMFC current respectfully. The efficacy and robustness of the proposed SMC and 2-SMC controllers are confirmed via computer simulations.