The present invention relates to a method of forming metallic foams using cold spray processing. The method allows for the formation of metallic foams on existing substrates as a layer. The method includes the steps of providing a substrate for coating of a metallic foam; cold spraying a mixture of metal particles and a foaming agent onto the substrate to form a substrate coated with an unexpanded metallic layer; foam heat treating the substrate coated with an unexpanded metallic layer at a temperature above the decomposition temperature of the foaming agent for a time sufficient to form a heated substrate coated with an expanded metal foam layer; and cooling the heated substrate coated with an expanded metal foam layer to about ambient temperature to form a cooled substrate coated with an expanded metal foam layer. The method of forming metallic foams on substrates finds application in the oil, gas, and chemical industry by being an integral part of casings, pipelines, transfer lines, and other flow lines.