In aqueous solution and at room temperature, various α-chloro-alkenes are effectively dechlorinated by hydrogen peroxide oxidation using a water-soluble ruthenium(II)-tetrasulfophthalocyanine catalyst, RuPcS. The molecular structure of RuPcS has been elucidated by ESI-mass spectroscopy. In the reaction conditions, and specifically in acidic media, the complex rapidly gives rise to a novel species, most likely catalytically active, whose nature is investigated.