Thin films of polymeric porphyrins have been made by interfacial polymerization of derivatives of tetraphenylporphyrins, in particular by condensation of a dichloromethane solution of the acid chloride derivative (TCCPP) with a buffered aqueous solution of either the amine derivative (TAPP) or the phenol derivative (THPP). Spectroscopic and other studies are consistent with cross-linked polyamide or polyester network structures. The polyamide and polyester films display a novel asymmetry of functional groups on opposite sides of the film; excess amine (or hydroxyl) groups appear on one side of the film and excess carboxyl groups on the other. Film thickness can be correlated with the intensity of the UV-visible absorption spectrum, x (in nm) = 120A(max) (at the Soret peak), with typical thicknesses in the range 10-500 nm, easily controlled by reaction time and conditions. Significantly thicker films (up to several mu m) can be prepared using an aliphatic diamine or polyamine as the comonomer with TCCPP. Addition of 2,6-lutidine to the organic phase substantially increases the rate of polymerization, which is especially useful for TAPP reactions. In addition, control experiments show that TCCPP with lutidine in CH2Cl2 reacts at the interface with an aqueous pH 3 buffer, giving a very thin, easily hydrolyzed film, apparently due to anhydride linkages formed by condensation reactions with partially hydrolyzed TCCPP.