The title compound, C9H10N4OS0.5H2O, crystallizes with two
independent molecules (A and B) in the asymmetric unit,
together with a water molecule of crystallization. The
acetamide moiety, which has an extended conformation, is
inclined to the pyridine ring by 7.95 (16) in molecule A and
by 1.77 (16) in molecule B. In the crystal, the A and B
molecules are linked by two N—H  Ocarbonyl hydrogen
bonds, forming a dimer. The dimers are linked via N—
H  N hydrogen bonds, forming ribbons that are linked by
N—H  Owater hydrogen bonds to form sheets parallel to
(110). The sheets are linked by O—H  N hydrogen bonds,
forming slabs, and between the slabs there are weak slipped
parallel – interactions [inter-centroid distance =
3.734 (2) A ° , interplanar distance = 3.3505 (11) A ° and slippage
= 1.648 A ° ], forming a three-dimensional structure.