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 Ba2Co1-xZnxS3 (0 <= x <= 1.0) series were studied using X-ray diffraction and electron microscopy. All members of the Ba2Co1-xZnxS3 series show the Ba2CoS3-type one-dimensional structure, but, after heating under pressure, the Ba2CoS3 compound (x = 0) separates into BaS and the two-dimensional BaCoS2-delta (delta approximate to 0), while Ba2Co1-xZnxS3 compounds with x >= 0.25 maintain their one-dimensional features but rearrange into polymorphs showing the Ba2MnS3-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.