Ammonia synthesis with catalyst derived by heating on a support a salt selected from alkali metal, alkaline earth metal, iron and cobalt hexacyanocobaltates and hexacyanoruthenates

A composition which can be heated at a temperature within the approximate range 325.degree.-430.degree. C. to activate the same to render it effective for ammonia synthesis at a relatively low temperature in the range 385.degree.-460.degree. C. which comprises on a suitable support at least one salt selected from the group consisting of an alkali metal hexacyanocobaltate, an alkaline earth metal hexacyanocobaltate, an alkali metal hexacyanoruthenate, an alkaline earth metal hexacyanoruthenate, iron hexacyanocobaltate, iron hexacyanoruthenate, cobalt hexacyanocobaltate and cobalt hexacyanoruthenate.