The mass-resolved, one-color, 2 + 1 resonance-enhanced multiphoton ionization spectrum of transient boron monochloride (BCl) between 348 and 369 nm is reported. Vibrational and rotational bands of the (BCl)-B-10-Cl-35, (BCl)-B-11-Cl-35, (BCl)-B-10-Cl-37, and (BCl)-B-11-Cl-37 isotopomers and two previously unreported electronic states are assigned. Rotational analysis identifies the F (1)Sigma(+) (3s sigma) state (nu(00) = 55994 +/- 10 cm(-1) for (BCl)-B-11-Cl-35). EE-EOM-CCSD ab initio calculations for BF and BCl support the F state assignment and suggest a tentative assignment of b (3)Sigma(+) (3p sigma) (nu(00) = 56864 +/- 10 cm(-1) for (BCl)-B-11-Cl-35). Uncertainties indicate the confidence of two standard deviations.