Sodium borohydride (NaBH4) is attractive as fuel for fuel cell hybrid electric vehicle (FCHEV) because of its high energy density. The authors have proposed and made a hydrogen generation system which uses sodium borohydride as fuel before now. However, as for this system, there has been a problem in the velocity of hydrogen generation under low-temperature water environment. This paper examined citric acid catalyst for improving velocity of hydrogen generation from sodium borohydride under low-temperature water. This paper clarifies that the generation velocity of hydrogen is improved by adding citric acid solution when hydrolyzing sodium borohydride. It was confirmed that there is not much problem in the power generation characteristics of a 100W fuel cell (FC), even if using rapid hydrogen generation system by adding citric acid solution.