The title compound, C18H14Cl2N2O, is an isomer of the triplet alkyl nitrene decay product formed upon photolysis of beta-azido propiophenone complexes. The molecule exhibits an overall twist with dihedral angles of 10.32 (7) and 24.94 (4)degrees between the pyrazole plane and the planes of the chlorophenyl rings. The crystal packing of the title compound features stacks of molecules in alternating orientations running along the b axis; the approximate separation distance between the planes of neighboring molecules in the stack is 3.66 angstrom.