Ethyl 2-chloro-[2-(4-chloro-phen-yl)hydrazin-1-yl-idene]acetate.

The title compound, C(10)H(10)Cl(2)N(2)O(2), features a planar C(ar)-N(H)-N=C(Cl) unit [torsion angle = 5.5†(4)°] whose benzene substituent is coplanar with it [dihedral angle = 4.7†(4)°]; this unit is slightly twisted with respect to the carboxyl -CO(2) fragment [dihedral angle = 2.2†(52)°]. The amino group acts as a hydrogen-bond donor to the carbonyl O atom of an adjacent mol-ecule; the hydrogen bond generates a helical polymer that runs along the b axis of the monoclinic unit cell.