The dissertation details the experimental work on the attempt to develop rhenium(V)phthalocyanine complexes directly from its +7 oxidation state (perrhenate). Different reducing agents (PPh3, Na2S2O5 and NaBH4) were employed and consequently, different results were acquired, such as rhenium(V)-mediated oxidative hydrolysis of the phthalocyanines (Pcs), the formation of a rhenium-phthalocyanine complex and phthalocyanine-capped nanoparticles. The rhenium nanoparticles that were formed were optimized from a synthesis point of view and, cancer localizing ability of the rhenium nanoparticles was investigated. The complexes were synthesized through direct metalation of pre-formed metal-free phthalocyanines using the “cold isotopes” of the rhenium metal. Rhenium nanoparticles (Re NPs) were synthesized in aqueous saline medium so as to imitate the environment on which Re is produced from its reactor. The nanoparticles (NPs) were capped with phthalocyanines which were covalently biofunctionalized with a folic acid moiety to enhance the targeting ability of the Re NPs. These NP systems were characterised with techniques such as ultraviolet-visible UV-Vis spectroscopy and transmission electron microscopy TEM. Cytotoxicity of the NPs was tested against four different cell lines and subsequently their cytotoxicity profiles were elucidated, and the profiles shown a dose-dependent responsealthough the results in some cell lines were unclear. Their fluorescence properties were also studied to provide photophysical information for investigation of their tumor localization using human cancer cells lines via confocal fluorescence microscopy studies. Particle size effect on localization of NPs was also investigated using confocal fluorescence and TEM. Two sizes were chosen (10 and 50 nm), and the smaller NPs (10 nm) were found to exhibit stronger fluorescence properties than the 50 nm NPs, and they were also found to have a better localization ability than the 50 nm NPs. Finally, their tumor and organ biodistribution studies will be carried out using micro-SPECT kits and model mice (using the “hot” isotopes in a radiopharmacy laboratory).