Atomic absorption spectroscopy has been used to measure the concentration of alkaline earth metal atoms as a function of hydrogen atom concentration in fuel-rich hydrogen + oxygen + nitrogen flames. In these flames, oxide formation is unimportant but both monohydroxides and dihydroxides are formed in significant amounts. For calcium, strontium and barium, the bond dissociation energies of the monohydroxides are respectively 104, 103, and 114 kcal mole–1 and of the dihydroxides are 204, 202 and 213 kcal mole–1.