Mass spectrometric studies of the gaseous equilibrium Pd + O reversible arrow PdO yield the dissociation energy D(0)degrees(PdO) = 56 +/- 3 kcal mol(-1). This new value is significantly lower than one recommended in the most recent review, D(0)degrees(PdO) = 90 +/- 20 kcal mol(-1), where an earlier value near 55 kcal mol(-1) was rejected because of higher values ranging from 90 to 98 kcal mol(-1) for neighboring metal monoxides. It is shown that the lower value reported here is consistent with the unique closed-shell structure of the Pd atom.