  We have produced sympathetically cooled barium monohalide ions BaX$^+$ (X =
F, Cl, Br) by reacting trapped, laser cooled Ba$^+$ ions with room temperature
gas phase neutral halogen-containing molecules. Reaction rates for two of these
(SF$_6$ and CH$_3$Cl) have been measured and are in agreement with classical
models. BaX$^+$ ions are promising candidates for cooling to the rovibrational
ground state, and our method presents a straightforward way to produce these
polar molecular ions.
