[4] The following hydrates crystallize from solutions of the proper composition in various temperature ranges:[5] Early reports of a monohydrate NaBO2·H2O have not been confirmed.

[5] Solid anhydrous sodium metaborate has the hexagonal crystal system with space group

[7] Infrared spectroscopy of the vapor from anhydrous sodium metaborate, heated to between 900 °C and 1400 °C, shows mostly isolated clusters with formula NaBO2, and some dimers thereof.

[8] Electron diffraction studies by Akishin and Spiridonov showed a structure O=B−O−Na with linear anion O=B−O− and angle B−O−Na of 90-110°.

[11] Electrolysis of a concentrated aqueous solution of 20%[clarification needed] NaBO2·4H2O with an anion exchange membrane and inert anode (such as gold, palladium, or boron-doped diamond) converts the metaborate anion to tetraborate B4O2−7, and the sodium salt of the later (borax) precipitates as a white powder.

[12] Sodium metaborate can be converted to sodium borohydride by several methods, including the reaction with various reducing agents at high temperatures and pressure,[12] or with magnesium hydride MgH2 by ball milling at room temperature, followed by extraction of the Na[BH4] with isopropylamine.