Abstract: A method of forming discrete magnetic particles in situ by dispersing a nickel hypophosphite solution in a binder and binder solvent, such as polyvinyl alcohol in water or polyester urethane polymer in an organic solvent, forming a coating from the nickel hypophosphite binder solution on a substrate, and exposing the coating to a radiant energy source, such as x-rays or an electron beam. Thereafter the incipient magnetic media in the area exposed to radiation is developed by contact with a solution including ions of at least one of cobalt, nickel and iron and a reducing agent, such as a hypophosphite ion, to produce a magnetic media of discrete magnetic particles within the binder in the area exposed to the radiant energy while not forming such magnetic particles in other unexposed areas of the nickel hypophosphite coating.