Highly efficient dehydrochlorination of PVC is feasible using a readily available ionic liquid, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). The process does not require additional organic solvents, catalysts, or pressure, and the ionic liquid can be recycled (at least 6 time) without appreciable loss of catalytic efficiency. Both anions and cations of the ionic liquids influence upon dehydrochlorination. This ionic influence, combined with the concerted elimination of HCl in a single step, accounts for the faster dehydrochlorination rate.