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

In the mol-ecule of the title compound, C(9)H(8)BrN(3)O, the fused-ring system is almost planar, the largest deviation from the mean plane being 0.008 (3) Å. The plane through the atoms forming the allyl group is roughly perpendicular to the imidazo[4,5-b]pyridin-2-one system, as indicated by the dihedral angle between them of 70.28 (11)°. In the crystal, each mol-ecule is linked to its symmetry equivalent about the center of inversion by a pair of strong N-H⋯O hydrogen bond, forming inversion dimers.