Production of isocyanic acid

A process for preparing isocyanic acid which comprises reacting a mixture of nitric oxide, carbon monoxide and hydrogen at a temperature of from about 200.degree. to 400.degree. C. in the presence of iridium or rhodium metal catalyst supported on a particulate carrier selected from the group consisting of silica, .gamma.-alumina, zirconium oxide and silicon carbide, said carrier further characterized in having a surface area, expressed as M.sup.2 /g, of not in excess of one, the contact time between said mixture and said catalyst being less than 1 second.