The title compound, (C₆H₁₁)3PS (systematic name: Tricyclohexyl-λ⁵-phosphanethione), is a triclinic (P-1, Z′ = 1) polymorph of the previously reported orthorhombic form (Pnma, Z′ = 1/2) [Kerr et al. (1977). Can. J. Chem. 55, 3081-3085; Reibenspies et al. (1996). Z. Kristallogr. 211, 400]. While conformational differences exist between the non-symmetric molecule in the triclinic polymorph, cf. the mirror-symmetric molecule in the orthorhombic form, these differences are not chemically significant. The major feature of the molecular packing in the triclinic polymorph is the formation of linear chains along the a axis sustained by methine-C-H⋯S(thione) interactions. The chains pack with no directional interactions between them. The analysis of the Hirshfeld surface for both polymorphs indicates a high degree of similarity, being dominated by H⋯H (ca 90%) and S⋯H/H⋯S contacts.