The crystal structure of the novel alcohol deri- vate from chlorthalidone, ethyl-chlorthalidone (2-chloro-5- (1-ethyl-3-oxo-1-isoindolinyl)benzenesulfonamide hydrated), C16H15ClN2O4S.H2O, was determined by X-ray diffraction at 295 K. This molecule crystallized in an orthorhombic space group Pca21 with a = 7.928(2) A ˚ ,b = 10.920(2) A ˚ , c = 19.459(4) A ˚ , a = b = c = 90. This compound is stabilized by intra and intermolecular NHO and OHO hydrogen bonds. These interactions which involve water molecules of the network give rise to a two-dimensional (2-D) array parallel to the (110) direction. The three- dimensional design of the compound is observed through weak NH��� O hydrogen bonds (N2-H2A��� O4). The NMR study was a complementary tool for crystal characterization. The spectra analysis clearly shows that signs of ethyl group atoms appear in strong field whereas the others atoms were identified in weak magnetic field (above of 140 ppm). The vibrational spectra present bands in the region of 2890-2940 cm -1 which can be assigned as symmetric and asymmetric modes of CH2 and CH3 groups. These results are in agreement with the crystal data which indicate the pres- ence of ethyl group in this molecule.