1-Acetyl-6-bromo-1H-imidazo[4,5-b]pyridin-2(3H)-one.

The two fused five- and six-membered rings in the mol-ecule of the title compound, C(8)H(6)BrN(3)O(2), are approximately coplanar, the largest deviation from the mean plane being 0.011 (3) Å at the NH atom. The acetyl group is slightly twisted with respect to the imidazo[4,5-b]pyridine system, making a dihedral angle of 2.7 (2)°. In the crystal, adjacent mol-ecules are linked by inter-molecular N-H⋯N and C-H⋯O hydrogen bonds, forming infinite chains.