Abstract: The invention is directed to the preparation of vinyl sulfide compounds of general formula —(—R1—S—R4C═CR5—R3—S—)n—(—R2—S—R4C═CR5—R3—S—)m, where m and n are integers in the range of 1-1000, are formed by the addition of a dithiol compound of general formula HS—R1—SH to an acetylenic compound of general formula HC≡C—R3—S—R2≡S—R3—C—CH2. These vinyl sulfide compounds can be homopolymerized or copolymerized with second monomers, oligomers or polymers that are capable of reacting with their carbon-carbon double bond. The vinyl sulfide compounds have a high refractive index (1.60 or higher at 632 nm) and can be used to make optical telecommunication elements and devices. They are soluble in selected solvents and such solutions can be applied to substrates by various methods such as spin coating, dipping, spraying and other methods known in the art.