In this article, introductory explanation for electrochemical measurements in high temperature aqueous solutions is presented. Although basics are common to normal electrochemistry at ambient temperatures, special attention is required to a reference electrode in an autoclave system because measured potential should be presented with respect to standard hydrogen electrode at given temperature. Two typical reference electrode systems, i.e. internal and external silver-silver chloride electrodes are explained in detail. Some examples of polarization measurements are also introduced.

Because of lack of test standards applicable in high-purity water at high temperatures, standardization of test methods for evaluating the stress corrosion cracking initiation of metals and alloys used for nuclear power plant has been carried out. The standard of uniaxial constant load test method has been established and stipulated in JSCE standard （JSCE S 1501）. The Japan industry standard （JIS G 0511） has been reviewed and modified for the rationalization of reverse U-bend test method. Furthermore, the attempt to reflect these discussed technical resolutions in ISO standard is currently ongoing.

We studied S₈ gas analysis method of S₈ gas released from sulfur vulcanized rubber duct installed in the engine room of vehicles. GC-MS and HPLC were used for gas analysis. As a result, HPLC could detect S₈ gas quantitatively. On the other hand, GC-MS failed to detect S₈ gas, because S₈ gas was trapped in the column and thus could not reach the mass spectrometer.

The influence of metal cations on corrosion of mild steel sheet was investigated by immersion tests and electrochemical impedance spectroscopy（ EIS） at high temperature using solutions of simulated fresh water. Immersion tests showed the different corrosion rates in different solutions, and the steel showed the minimum corrosion in the solution containing Zn^2＋. Surface morphology changes of steel due to corrosion by the metal cations were carried out by scanning electron microscopy （SEM）. Measurement of the charge transfer resistance （R_ct） and XPS results suggested that Zn^2＋ exists on the steel surface by forming a layer, thereby improving the protective property of the passive films of mild steel.

Decamethyleneimine（CH₂）₁₀ NH has been proposed to be an effective inhibitor due to a π-characterized unshared pair of electrons on the N atom deformed by strain in the ring to near 120° of C-N-C bond angle. It is concluded in this paper that the N atom in the sp² hybrid orbital geometry is classified as a soft base and the bare iron surface belongs to a soft acid, resulting in the formation of a stable chemisorption bond and hence, in the enhanced inhibition efficiency.

The corrosion would often progress with the mutual interaction between adjacent defects, especially at some locations of paint-coated steel structures where the rainwater or dew stagnated in long-term, because of the occurrence of electrical short circuit around the multiple coating defects.

The objective of this study is to investigate the electrochemical mechanism of mutual interaction between the adjacent coating defects in a stagnant water environment. The model specimens embedded with a plurality of electrodes were fabricated to simulate coating defects, and the corrosion currents were measured between these electrodes. In case of the two electrodes with different diameters, the measurement results show that the anode reaction would be fixed in the electrode with a relative larger diameter, while the cathode reaction would be fixed in the electrode with a small diameter. In addition, when the diameter of the electrode is less than 20 mm, it has been clarified that the linear correlation exists between the area ratio of adjacent electrodes and the macrocell current density, and the relationship was formulated.