(E)-3,4-Dihydroxy-benzaldehyde 4-methyl-thio-semicarbazone.

The title compound, C(9)H(11)N(3)O(2)S, adopts an E configuration with respect to the C=N bond. The mol-ecule is approximately planar, with an r.m.s. deviation from the mean plane through all 15 non-H atoms of 0.152 Å; the dihedral angle between the benzene ring plane and the least-squares plane through the thio-semicarbazone unit is 12.48 (7)°. A weak intra-molecular N-H⋯N inter-action contributes to the planarity of the semicarbazone unit. Centrosymmetric pairs of O-H⋯O and N-H⋯S hydrogen bonds form chains along c, generating R(2) (2)(10) and R(2) (2)(8) ring motifs, respectively. In the crystal structure, these chains are further linked by inter-molecular O-H⋯S and C-H⋯O inter-actions, forming stacks down the c axis.