This invention relates to a method to improve 1, 1,3-trichloropropene selectivity in HCC-250fb (1,1,1,3-tetrachloropropane) dehydrochlorination. In normal practice, FeCl3 is used as the catalyst for the dehydrochlorination of HCC-250fb to produce 1,1,3-tri-chloropropene. In this invention as source of water is added into the reaction system to inhibit the formation of high boiling compounds such as pentachlorocyclohexene and/or hexachlorocyclohexane. Once source of water is H
2 O itself. Another source of water is one or more hydrated metal halides.