Abstract: An instrument is applied to the measurement of chemical species and concentration through the use of a chemically-sensitive coating on the eddy current coil or in the vicinity of the eddy current coil which produces a change in impedance of the probe through induced eddy currents in the coating. An eddy current or resonance circuit chemical detector is a non-contact sensor for measuring chemical species identity and concentration. The chemical detector is resilient and does not require reference electrodes. The chemical sensor is selective as a result of data available on the change in vector impedance of the probe, the change in resonant frequency of the tuned circuit, and the availability of data to construct a vector response from multiple probes having differing chemistries. The probe is used in extreme temperatures.