Addition of boron to atmospheric-pressure fuel-rich H2+ N2+ O2 flames seeded with alkali metals results in reductions in concentrations of free alkali metal atoms and in formation of negative boron-containing ions. The following enthalpy changes and equilibrium constants are inferred: Li + HBO2â LiBO2+ H Î H°0=â 21 ± 20 kJ mole^{â 1}, K= 15 exp (2300/T). Na + HBO2â NaBO2+ H Î H°0=+ 21 ± 20kJ mole^{â 1}, K= 12 exp (â 3000/T). K + HBO2â KBO2+ H Î H°0=+ 8 ± 20 kJ mole^{â 1}, K= 37 exp(â 2500/T). HBO2+ e^ââ H + BOâ 2Î H 0°=+ 94 ± 20kJ mole^{â 1}, K= 1.5 à 10³ exp (â 10000/T). These enthalpy changes, when combined with JANAF data for HBO2, BO2, H, K, Na and Li, lead to standard heats of formation at 0 K of â 636 ± 25 kJ mole^{â 1} for LiBO2(g), â 644 ± 25kJ mole^{â 1} for NaBO2(g) and â 674 ± 25kJ mole^{â 1}for KBO2(g), and provide a value for the electron affinity of BO2of 393 ± 20 kJ mole^{â 1}.