Abstract. Ammonia synthesis requires high pressure and high temperature process. Unfortunately, the capital intensive cost resulting low yield of ammonia by using recent catalyst which is iron oxide. Therefore, manganese zinc ferrite as a soft ferrite material will be introduced as a new nanocatalyst to enhance the ammonia yield. As a new nanocatalyst for ammonia production, study of comparasion two different concentration of MnZn Ferrite is very important. This paper will compare the yield of ammonia by using two different nanocatalyst which are Mn 0.4 Zn 0.6 Fe 2 O 4 and Mn 0.6 Zn 0.4 Fe 2 O 4 . Both were synthesized by sol-gel method and has been characterize by using FESEM (morphology), XRD (phase identification), EDX (elemental analysis) and TPR (oxide reduction). The ammonia was produce with and without magnetic field applied. The result shows that the ammonia yield is higher for Mn 0.4 Zn 0.6 Fe 2 O 4 nanocatalyst than Mn 0.6 Zn 0.4 Fe 2 O 4 by using magnetic field applied. 67.2% of yield has been achieved by using new nanocatalyst Mn 0.6 Zn 0.4 Fe 2 O 4 and magnetic field applied at ambient environment.