BF3 is commonly referred to as "electron deficient," a description that is reinforced by its exothermic reactivity toward Lewis bases.

BF3 is manufactured by the reaction of boron oxides with hydrogen fluoride: Typically the HF is produced in situ from sulfuric acid and fluorite (CaF2).

Suitable metals for equipment handling boron trifluoride include stainless steel, monel, and hastelloy.

[17] All three lighter boron trihalides, BX3 (X = F, Cl, Br) form stable adducts with common Lewis bases.

Such measurements have revealed the following sequence for the Lewis acidity: This trend is commonly attributed to the degree of π-bonding in the planar boron trihalide that would be lost upon pyramidalization of the BX3 molecule.

As a consequence, the bond length between boron and the halogen increases while going from fluorine to iodine hence spatial overlap between the orbitals becomes more difficult.

In an alternative explanation, the low Lewis acidity for BF3 is attributed to the relative weakness of the bond in the adducts F3B−L.

The reaction commences with the formation of the aquo adduct, H2O−BF3, which then loses HF that gives fluoroboric acid with boron trifluoride.

[22] The heavier trihalides do not undergo analogous reactions, possibly due to the lower stability of the tetrahedral ions [BCl4]− and [BBr4]−.