The crystal and molecular structure of the title compound, C₁₉H₂₁NO₅S, M = 375.44, was solved by X-ray structure analysis using diffractometer intensity measurement with CuK_α radiation. The space group is P1, with lattice parameters a = 555.7(3), b = 1 697.0(8), c = 1 035.4(4) pm, α = 106.77(4)°, β = 98.19(4)°, γ = 90.64(4)°, V = 923.9(8) . 10⁶ pm³, Z = 2, ρ_calc = 1.349 g/cm³, ρ_m = 1.32 g/cm³. Anisotropic refinement of all nonhydrogen and isotropic refinement of eight hydrogen atoms converged to R = 0.056 and wR = 0.114 for 2 481 observed reflections. Hydrogen bonds O18-H181···O25 and N9-H91···O24ⁱ join neighbouring diphenyl sulphide and maleate molecules to linear chains. The parallel chains interact through van der Waals contacts only. Molecules of maleic acid are nearly planar keeping π-electron delocalization. An angle between phenyl rings of the diphenyl sulphide molecule is 80.9(1)° and torsion angles around S-C bonds are 23.2(3)° and 73.6(3)°.