Organometallic conjugated polymers containing transition metal centers in the main chain (polymetallynes), with general formula -[M-(PBu3)(2)-C C-X-C C-](n)- with M=Pt(II) and Pd(II), X = organic conjugated spacer, namely poly[ 1,1'-bis(ethynyl)-4,4'-biphenyl-(bis-tributylphosphine)Pd(II)] (Pd-DEBP), poly[1,1'-bis(ethynyl)-4,4'-biphenyl-(bis-tributylphosphine)Pt(II)] (Pt-DEBP) and poly-[1,4-bis(ethynyl)-2,5-dihexadecyloxybenzene-bis(triphenylphosphine) platinum(II)] (Pt-BOB) were synthesized and fully characterized. The polymeric compounds were cast deposited onto glass substrates and their morphologies studied by means of SEM (Scanning Electron Microscopy) and EF-TEM (Energy Filtered-Transmission Electron Microscopy). The formation of nanostructured fibrils with diameters in the range 100-300 nm was revealed by SEM. EF-TEM images showed that the fibers are made of hollow nanotubes, randomly oriented, with external diameter of about 6-7 nm. (C) 2008 Elsevier Ltd. All rights reserved.