The annual cost of corrosion in the US is estimated at roughly 6% of the gross national product. According to a study by the Federal Highway Administration (FHWA 2006), the annual direct cost of corrosion in the transportation infrastructure category alone (highway bridges, waterways and ports, hazardous materials storage facilities, electrical utilities, airports, and railroads) is estimated at tens of billions USD and higher by more recent estimates (Kutz 2012; Nace et al. 2002; Jackson 2017). In general, the costs of repair and remediation to the civil infrastructure are higher than necessary when maintenance schedules are not based on a clear understanding of the onset of damage (for example corrosion), and the degree to which deterioration has occurred, for example, internal cracking. Chemical sensors can play a particularly important role in early detection of deterioration. In corrosion, the processes generally start by releasing ionic components that can be sensed in advance of the appearance of physical signs of damage. This chapter highlights the development of chemical sensors for the detection of iron and zinc.