The PtCl_4 and H_2PtCl_6·6H_2O doped polyacetylene were studied by X-ray photoelectronspectroscopy and transmission electron microscopy.We found that both Pt 4f and Cl 2p peaks couldbe resolved into two components both with a splitting of ca.1.5 eV.The higher binding energycomponents of Pt 4f peak is attributed to Pt~(4+) and the lower binding energy one to Pt~(2+) species.Fromquantitative analysis of the results of decomposition of both Pt 4f and Cl 2p peaks it was found thatan atomic ratio of chlorine to platinum for Pt~(2+) species is(Cl)/(Pt)2 and that for Pt~(4+) speciesis (Cl)/(Pt)6 for both PtCl_4 and H_2PtCl_6·6H_2O doped polyacetylene.The C 1s peaks could bedecomposed into two components separated by ca.1 eV.The intensity of the higher binding energycomponent increased with increasing dopant concentration.These indicate that the platinum saltdoping proceeds through charge transfer from polyacetylene chain to platinum atom resulting ina partial reduction from Pt~(4+) to Pt~(2+) state.The existence of PtCl_2 cluster on the surface of the dopedpolyacetylene film was supported by transmission electron microscopy and electron diffraction obser-vations.These results indicate that a random distribution of the dopant along the macromolecularchain,and the charge per carbon atom in the metallic region of doped polyacetylene has been estimatedto be 0.2|e|.From these results the mechanism of the PtCl_4 and H_2PtCl_6·6H_2O doping process inpolyacetylene is clarified as follows:2PtCl_4+2e——PtCl_6~(2-)+PtCl_2 for PtCl_4 doping;2H_2PtCl_6+2e——PtCl_6~(2-)+PtCl_2+4HCl for H_2PtCl_6·6H_2O doping.Thus the dopant anion in polyacetylene is PtCl_6~(2-) for both PtCl_4 and H_2PtCl_6·6H_2O doping. The PtCl_4 and H_2PtCl_6 · 6H_2O doped polyacetylene were studied by X-ray photoelectronspectroscopy and transmission electron microscopy. We found that both Pt 4f and Cl 2p peaks could be resolved into two components both with a splitting of ca.1.5 eV. The higher binding energycomponents of Pt 4f peak is attributed to Pt ~ (4+) and the lower binding energy one to Pt ~ (2+) species. Popular quantitative analysis of the results of decomposition of both Pt 4f and Cl 2p peaks it was found that an atomic ratio of chlorine (Pt) 2 and that for Pt ~ (4+) speciesis (Cl) / (Pt) 6 for both PtCl_4 and H_2PtCl_6 · 6H_2O doped polyacetylene.The C 1s peaks could bedecomposed into two components separated by ca.1 eV. the intensity of the higher binding energycomponent increased with increasing dopant concentration. the sense that the platinum saltdoping proceeds through charge transfer from polyacetylene chain to platinum atom resulting in partial reduction from Pt ~ ( 4+) to Pt ~ (2 +) state. The existence of PtCl 2 cluster on the surface of the doped polyacetylene film was supported by transmission electron microscopy and electron diffraction obser- vations. The result of that indicates that a random distribution of the dopant along the macromolecular chain, and the charge per carbon atom in the metallic region of doped polyacetylene has been estimated to be 0.2 | e | .From these results the mechanism of the PtCl_4 and H_2PtCl_6 · 6H_2O doping process inpolyacetylene is clarified as follows: 2PtCl_4 + 2e - PtCl_6 ~ (2 -) + PtCl_2 for PtCl_4 doping; 2H_2PtCl_6 + 2e - PtCl_6 ~ (2 -) + PtCl_2 + 4HCl for H_2PtCl_6 · 6H_2O doping.Thus the dopant anion in polyacetylene is PtCl_6 ~ (2-) for both PtCl_4 and H_2PtCl_6 · 6H_2O doping.