Book excerpt: In response to significant developments in sensor science and technology, this book offers insight into the various extended applications and developments of N4 macrocycle complexes in biomimetic electrocatalysis. Chapters are devoted to the chemistry, electronic and electrochemical properties of porphyrin- based polymetallated supramolecular redox catalysts and their applications in analytical and photoelectrochemical molecular devices; the use of porphyrins, phthalocyanines and related complexes as electrocatalysts for the detection of a wide variety of environmentally polluting and biologically relevant molecules; and the use of electropolymerized metalloporphyrin and metallophthalocyanine films as powerful materials for analytical tools, especially for sensing biologically relevant species.