This chapter evaluates the through-porosity of the high velocity oxy-fuel (HVOF) sprayed HastelloyC coating on SS400 carbon steel with respect to its dependence on the coating thickness and on the combustion pressure upon spraying. The through-porosity of the coating for HVOF sprayed HastelloyC was evaluated by the chemical analysis of the dissolved substances permeating by way of the through-porosity of the coating using the inner centrifugal projection emission spectrometry. The through-porosity of the HVOF sprayed coating was evaluated by the chemical analysis and the electrochemical measurements. The coatings of HVOF sprayed SUS316L stainless steel and HastelloyC nickel-base alloy have been investigated with respect to the relation between the spray condition and their properties such as the porosity, the oxygen content, and the corrosion resistance. From the results of the electrochemical measurements, the corrosion potential explained well the relative order of amount of the through-porosity and its abrupt increase. Paper includes a German-language abstract.