Phosphine ligands bearing 3,4-ethylenedioxythiophene (EDOT) groups, in which a Ph₂P group is either connected directly to the thiophene ring [Ph₂P(5–EDOT), 1] or to the EDOT ethylene bridge via a methylene (4) or longer (7) ‘spacer’, have been prepared, together with their complexes cis-[MCl₂(L)₂] (M = Pd and Pt). The electrochemical co-polymerization of the complexes with EDOT was investigated, with a view to making conducting polymers incorporating covalently-bound metal–phosphine complexes. Although polymer-coated electrodes were obtained in all experiments, XPS measurements established that polymers made in the presence of cis-[MCl₂(1)₂] consisted only of poly(3,4-ethylenedioxythiophene) (PEDOT), whereas polymers made in the presence of cis-[MCl₂(L)₂] (L = 4, 7) were genuine co-polymers containing Pd(II) or Pt(II) complexes.