The method of study was to measure timedependent changes of the electrode potential and electrical resistance of static, palladized wires immersed in well-stirred solutions. Desorption rates were compared in both nitrogen and argon-saturated solutions. Results confirmed that nitrogen can be effectively regarded as a chemically inert atmosphere during investigations of the kinetics of hydrogen evolution at platinum and palladium electrodes.Oxidants studied were : oxygen, potassium dichromate, potassium pemanganate, ceric sulphate, hydrogen peroxide, chlorine, bromine and iodine ; where possible data were obtained both in neutral and acidic solutions. Excepting iodine and bromine, and in the absence of the formation of insoluble oxides, results show that far concentrations of oxidant approaching 0 2 g equiv./l. the kinetics of hydrogen removal are (irrespective of the hydrogen content of the solid) primarily governed by the transport of oxidant through solution to the surface of the hydride.Palladium can absorb much hydrogen at 25°C and titrimetry with strong oxidizing agents has been employed to measure the hydrogen content.1-5 Studying the kinetics by means of relationships between electrical resistance and hydrogen content, Knorr 6 had earlier proposed, as a consequence of the rapidity of diffusion of hydrogen in the solid hydrides and of the rapidity of reaction steps at their surfaces, that the removal of hydrogen by acidified potassium dichromate should be generally governed by the rate at which the oxidant could diffuse through the Brunner-Nernst layer. Doubt regarding the viability of using changes of the electrical resistance of palladium for such experimental purposes, has been largely discounted in a recent investigation.5In addition to examining the kinetics of oxidation with a wider range of oxidants, the purpose of the present investigation was also to try and correlate the results with other work in which the main attention has been centred on the absorption of hydrogen by palladium. EXPERIMENTAL MATERIALS Palladium (>99.99 % pure) wire specimens of 0-0122 cm diam. (International Nickel Co. (Mond.) Ltd.) and ca. 12 cm in length were used for the majority of the experiments. Specimens of 0.0025 cm diam. (Johnson Matthey) were ca. 5 cm long and specimens of 0.0274 cm diam. (Johnson Matthey) were ca. 15 cm long. A l l specimens were welded toplatinum leads as previously described7 and the weld covered by soda glass. Solutions of oxidizing agents were prepared from A.R. reagents without further purification. All gases were obtained from commercial cylinders. Nitrogen was B.O.C. oxygen-free-White Spot. APPARATUSDuring absorption of hydrogen, specimens were generally immersed in electrolyte contained in a Pyrex glass vessel, similar to one previously described 7 but divided into two identical compartments (A, A') by a sintered glass disc (porosity 4). Two gas streams

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