Over 10 days of exposure in 0.05 M NaCl solution, Ni coaling with mean crystallite size of 6 nm deposited in ChCl:EG deep eutectic solvent corrodes with diffusion constraints. Native oxide layer (4.7 nm thick) is a mixture of NiO and NiOOH. During exposure, NiO forms on the top of the layer of corrosion products, whose thickness exceeds 15 nm after 10 days. Double layer capacitance increases due to the growth of the active surface. Thickening of the layer and diffusion limitations leads to the increase in charge transfer resistance from teens of k Omega cm(2) to 220 k Omega cm(2).