| The borohydride is hydrogen source for an advanced fuel cell, Imol borohydride with water produces 4mol hydrogen and Imol of side product sodium metaborate. Regeneration of metaborate for recycle of boron brings forth a bright future to the new fuel cells. In this paper, a method for the preparation of sodium borohydride from sodium metaborate was proposed. According to the thermodynamics , the value of enthalpy, entropy, Gibbs free enthalpy, it was discussed the possibility of reduction of sodium metaborate to produce sodium borohydride. The requirements were respectively investigated in terms of the criterions of Gibbs function and electromotive force. In an experimental electrolytic cell, the electrolyte was sodium hydroxide with a concentration of1mol.L-1, the minimal cell voltage should be -2.469V at ambient conditions; and Cu was used as the cathode, the applied current density was 0.1A.cm-2. Under the conditions above, it was calculated that the equilibrium potentials of the main reaction and the side reaction of hydrogen precipitation were -1.26V and -1.67V respectively. The hydrogen precipitation of different metals, platinum, lead, nickel, iron and titanium, were discussed in different pH value and current density. By using Cyclic Voltammetry to study the reduction reaction, copper, titanium, lead, Ti/PbO2 and Ti/MnO2 as cathode respectively, it is proved that sodium metaborate can be electrochemically reduced to sodium borohydride. The kinetic parameters and fractal dimension of these electrode, graphite, lead iron Ti/PbO2 and Ti/MnOa etc, will be researched. The Ti/PbO2 was believed the best electrode materials. The regularity of diffuse was studied using Pt/C RDE. Qualitative and quantitative analysis were used to measure it, such as, iodimetry, ion chromatography and open circuit potentials. The XRD was used to as a token way. it is proved that sodium metaborate can be electrochemically reduced to sodiumborohydride.
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