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Brasses and bronzes are one of the most widely utilised families of materials, ranging from, bathroom fixtures, zippers on clothes, electronic hardware, automotive bearings, munitions, corrosion-resistant marine fixtures, world coin currencies and many more. Recently, a range of new high entropy brasses and bronzes (HEBs) from Cu-Ni-Mn-Zn-Al alloy system have been developed as cost-effective commodity brass and bronze replacements. These alloys represent a significant shift from the tradition ‘solventrich’ copper-rich alloys, effectively lowering the copper content and utilising larger quantities of multiple elements in unison, giving rise to some exceptional mechanical and microstructural properties. This project intends to explore the evolution of the corrosion and electrochemical behaviour of high entropy brasses and bronzes (HEBs), beginning with the binary alloy systems, extending to ternary and quaternary elemental combinations (including CuNi, Cu-Al, Cu-Mn, Cu-Zn, Cu-Mn-Ni, Cu-Ni-Al, Cu-Mn-Zn, Cu-Mn-Al, Cu-Ni-Zn, Cu-Mn-Ni-Zn). The complex effects of both independent elements and elemental combinations on corrosion characteristics and several kinds of known de alloying phenomena are investigated, establishing a systematic database of the corrosion performance of multicomponent copper-based alloys. In this work, open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements were carried out in accordance with ASTM standards in a 3.5 wt.% neutral NaCl solution (simulated seawater) of pH 7.0 at 25℃. Of the sixty-six alloys examined, a broad spectrum of corrosion characteristics were observed in this corrosion environment. Generally, alloys with high Ni-content display exemplary electrochemical behaviour owing to the formation of a protective oxide film, whilst ternary alloys with high Mn-, Zn- and Al-content possess relatively low corrosion resistance due to extended dealloying phenomenon. The Cu60Mn10Ni30 alloy (in atomic %) displayed the most favourable combination of corrosion character with a corrosion rate of 10.3 μm·year-1 whereas the Cu80Mn15Al5 alloy exhibited the least favourable corrosion characteristics, with a corrosion rate of 142.4 μm·year-1. Interestingly, it was found that the quaternary HEBs with an Mn-content of 15-25 at.% and a Zn-content of 15-20 at.% (Cu60Mn15Ni5Zn20, Cu60Mn20Ni5Zn15, Cu55Mn20Ni5Zn20 and Cu55Mn25Ni5Zn15) have outstanding corrosion performance, noticeably superior to that of pure Cu (92.4 μm·year-1) and the majority of alloys studied in this work.