The thesis is presented in two parts, part one concerns the synthesis and biodistribution of technetium–porphyrin complexes. A series of compounds with the general formula TcO(Porhyrin)OAc and TcO(Phthalocyanine)OPh have been synthesised via a novel route. The starting material comprised NH4TcO4 with acetic acid for the porphyrin and phenol for the phthalocyanine. The compounds have been characterised both qualitatively and quantitatively by infra-red, ultra-violet and mass spectrometry. Thin Layer Chromatography (TLC) and electrophoresis have also been employed to further analyse the complexes. Preliminary biodistribution studies have been performed in a model of inflamed tissue. The results suggest that the labelled porphyrins are capable of imaging such tissue. One of the complexes was tested for an ability to accumulate in, and image tumours, however this proved unsuccessful.