Acetylene undergoes hydrochlorination by gaseous HCl in the absence of a solvent during mechanical treatment of K2PtCl6 powder. Acetylene consumption and vinyl chloride formation do not stop when mechanical treatment is interrupted. In the DCl atmosphere, trans-D-vinyl chloride is formed. It was assumed that the catalytic reaction proceeds on the active sites, which are K2PtCl6 lattice defects in the form of topologically bound Couple PtCl42--PtCl5- generated by mechanical pre-activation of K2PtCl6 salt under acetylene. Reaction begins with acetylene chloroplatination by a coordinatively unsaturated Pt(IV) complex producing intermediate formation of beta-chlorovinyl Pt(IV) derivative. The complementary reduction of this intermediate by Pt(II) yielding the corresponding Pt(II) organometallic derivative and protonolysis of the latter species result in vinyl chloride formation and regeneration of active site of the catalyst. (C) 2003 Elsevier B.V. All rights reserved.