Proton exchange membrane fuel cell (PEMFC) is the most promising energy source for the robot applications because it has unique advantages such as high energy density, no power drop during operating, and easy to make compact size. However, PEMFC has intrinsic disadvantages which are delay to start up and difficulty to correspond drastic load changes. These disadvantages can be compensated by hybrid operating with a Li-poly battery. This study is focus to build and understand the hybrid system for the robot system. In this study, we build the PEMFC hybrid system using EOS-320 PEMFC stack, Li-poly battery and G-Philos FDX1-250BU dc-dc converter. The hybrid system is accurately monitored by CAN and RS485. The system was studied under two conditions such as non-loaded and loaded operating conditions. The results show that the system has delay to start up without hybrid operating and it can be compensated with the hybrid operating.