The synthesis of covalently linked porphyrin dimers and trimers is described. Mono- and dihydroxyporphyrins were synthesized by transesterifying 5,10,15,20-tetra(4-carbomethoxyphenyl)porphyrin with ethylene glycol. The mixture of transesterified porphyrins were separated by preparative TLC. Metal derivatives were made of the mono- and dihydroxyporphyrins and these were reacted with the acid chloride of a monocarboxyporphyrin to yield hybrid dimers and trimers containing 1 metalloporphyrin and either 1 or 2 free base porphyrins. The structures and purity of the dimers and trimers were established by measuring the absorbance spectra, NMR spectra and molecular weight by gel permeation chromatography.