The development of a new way to synthesize oxamide, controlled-release nitrogen fertilizer, from coal and ammonia was investigated. The optimum conditions for the oxidation of coal in alkaline solutions were determined under which the yield of oxalic acid reached 90 wt% or more. The alkali-catalyzed oxygen-oxidation mechanism was confirmed by the kinetics with model compounds.  Crude sodium oxalate containing 6% sodium carbonate was easily recovered from the oxidation products. A phase diagram of the (COONa)₂-(NH₄)₂ (HCO₃)₂-H₂O system was constructed for the double decomposition reaction to obtain ammonium oxalate monohydrate from sodium oxalate.  Acid catalysts were found to promote the thermal dehydration reaction in the thermal decomposition of ammonium oxalate monohydrate to oxamide and its yield reached 86%.