In summary, we identified the novel hydrogen-producing green alga as Tetraspora sp. CU 2551. Tetraspora sp. has high potential to produce an alternative energy source, molecular biohydrogen. They grow fast at 36 ○C with the low-cost medium (TAP) under light condition. With the optimal condition, Tetraspora can evolve the significant amount of hydrogen yielding about 0.6 μmol/mgDW/h.