The initial growth behavior and structures of free base and metal complexes of 5,10,15,20-tetrakis (3,5-di- t -butylphenyl) porphyrin (H₂ -TBPP, M-TBPP) of Cu (100) surface were studied by scanning tunneling microscopy. Conformational flexibility of H₂ -TBPP led to bridging over the step edges and to formation of single supramolecular chains on the edges, which were separated from the supramolecular islands on the terraces. M-TBPP adsorbed on the upper and lower edge of the step and 2D growth of islands began from here. These results suggest that the step edges could be useful as a template for fabrication of well-ordered single supramolecular chains.