Sodium tetrahydroborate is the most attractive chemical hydride for H2 generation and storage in automotive fuel cell applications,but recycling from the by-product(NaB(OH)4) is difficult and costly.An electrochemical regeneration process could represent an economically feasible and environmentally friendly solution.The micro-Structure and physicochemical properties such as the volumetric and the transport properties at moderate temperatures affect the H2 generation and storage system as well as the electrochemical recyclability of the by-product.Density,electrical conductivity,pH,viscosity and Raman spectra of aqueous NaB(OH)4 solutions were precisely measured.Polyborate distribution in aqueous NaB(OH)4 solutions at 298.15K and 323.15K was calculated using measured pH value and literatural equilibrium constant.