New platinum chain compounds, $[M(en)_2]_{0.80}[Pt(ox)_2]{cdot}2H_2O$ where M = Cu or Pt, en = ethylenediamine and ox = oxalate, have been prepared and found to have a commensurate Peierls structure as evidenced by the five-fold Pt chain periodicity and unusually low electrical conductivity $(1.5{ imes}10^{-5}{sim}5.7{ imes}10^{-3}S/cm)$. Including two other compounds with the Peierls structure, their characteristic features were deduced and explained from the point of view of the band theory.