**7. Conclusions**

Hydrogen produced from electrolytic, biological, steam reforming and photocatalytic methods can be utilized as a clean energy source. Still, plenty of research and development is needed to enhance the efficiency and to reduce the overall economy of the process. Though the various hydrogen production methods which are discussed here are better and less expensive, an effective method need to be developed for future energy crises. Photocatalytic hydrogen generation from water and hydrogen sulfide splitting using available setup is with opportunities to development for young researchers. Besides the transportation and storage of hydrogen gas it must be considered in a frame of the energy system globally.
