C22H29N3OS.H2O, M(r) = 401.57, monoclinic, P2(1)/c, a = 6.511 (1), b = 14.914 (3), c = 22.550 (4) angstrom, beta = 97.84 (1)-degrees, V = 2169.1 angstrom 3, Z = 4, D(x) = 1.23 g cm-3, lambdaBAR(Cu K-alpha) = 1.54178 angstrom, mu = 14.59 cm-1, F(000) = 864, room temperature, R = 0.058 for 1270 observed reflections. This compound is a centrally active hypotensive agent. The molecule can be described by two planar moieties, i.e. the methylphenyl group and the [(4-acetamidophenyl)thio]propane group substituting a piperazine ring in a chair conformation. The overall conformation is trans extended.