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The presence of nitric oxide NO in the gas phase was shown to decrease the decomposition rate of the hydrotalcite-like Co–Al LDH phase in the catalysts prepared by co-precipitation or deposition on Al 2 O 3 under the condition of urea hydrolysis. The decrease in LDH decomposition rate is related to the formation of a more crystallized phase of the spinel-like Co–Al oxide due to the ability of nitric oxide to transfer oxygen in consecutive reactions of the oxidation to NO 2 and reduction to NO. The difference in the coherent scattering domain size of the catalyst samples precalcined in the presence of NO or in a pure inert gas is retained at all consecutive steps of the reductive heat treatment in hydrogen: after the formation of a cubic phase of the (Co, Al)O oxide and its reduction to metallic cobalt. The observed changes in the degree of crystallinity and dispersion of the active metal exert only a slight effect or even no effect on the activity of the catalysts in Fischer–Tropsch synthesis. Noteworthy are a lower selectivity for methane and a greater fraction of olefins in the products obtained on the catalysts precalcined in a flow of inert gas containing 3% NO. [ABSTRACT FROM AUTHOR]