Borohydrides present interesting options for electrochemical power generation acting either as hydrogen sources or anodic fuels for direct borohydride fuel cells and batteries. Though there have been several papers concerning electrochemical determination of relevant thermodynamic and kinetic parameters to the borohydride system, there are a number of basic aspects that have not been yet systematically studied. This paper reports chronopotentiometric studies of the electrooxidation of sodium borohydride at a gold sphere electrode in 2M NaOH solutions, at temperatures ranging from 25 to 65°C. Gold displayed a rather good borohydride oxidation activity, and the overall oxidation process was shown to be irreversible involving a number of electrons very close to the theoretically expected value of 8. The results suggested that the rate-determining step is an irreversible, diffusion controlled, one-electron oxidation step, for which the transfer coefficients were calculated.
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