In this work, high pressure was used as a tool to induce structural transition and prepare metastable polymorphs of ternary sulfides. Structural transformations under high pressure of compounds belonging to the Ba(2)Co(1-x)Zn(x)S(3) (0 ≤ x ≤ 1.0) series were studied using X-ray diffraction and electron microscopy. All members of the Ba(2)Co(1-x)Zn(x)S(3) series show the Ba(2)CoS(3)-type one-dimensional structure, but, after heating under pressure, the Ba(2)CoS(3) compound (x = 0) separates into BaS and the two-dimensional BaCoS(2-δ) (δ ≈ 0), while Ba(2)Co(1-x)Zn(x)S(3) compounds with x ≥ 0.25 maintain their one-dimensional features but rearrange into polymorphs showing the Ba(2)MnS(3)-type structure. All structural transformations can be linked to shortening in interchain metal-metal distances caused by the high pressure, and the role of the zinc in preventing loss of one-dimensionality is discussed.