The x-ray detection capability of a scintillation detector equipped with a BaCl2 single crystal was evaluated. The scintillation decay kinetics can be expressed by a sum of two exponential decay components. The fast and slow components have lifetimes of 1.5 and 85 ns, respectively. The total light output is 5 that of YAP:Ce. A subnanosecond timing resolution was obtained. The detection efficiency of a 67.41 keV x-ray is 87 for a detector equipped with a BaCl2 crystal 6-mm thick. Thus, excellent timing resolution and high detection efficiency can be simultaneously achieved. Additionally, luminescence decay characteristics under vacuum ultraviolet excitation have been investigated. Radiative decay of self-trapped excitons is thought to be responsible for the fast scintillation component.