Biodiesel was successfully produced by transesterification process of soybean oil and methanol using Ni0.5Zn0.5Fe2O4 nanomagnetic catalyst. The Ni0.5Zn0.5Fe2O4 catalyst was synthesized by the combustion method and its properties were investigated using X-ray diffraction, N-2 physisorption at 77 K, Fourier transform infrared analysis, thermogravimetric analysis, scanning electron microscopy, and a transmission electron microscopy. The performance of catalyst was investigated during transesterification reaction for fatty acid methyl esters (FAMEs) production. FAMEs were studied by gas chromatography technique. The effect of reaction conditions such as molar ratio of methanol/soybean oil, catalyst amount, reaction temperature, and reaction time on FAMEs yield was also evaluated. The biodiesel yield of 92.1% was obtained under the following reaction conditions: 9:1 of methanol/soybean oil molar ratio and, 2% of catalyst loading at 180 degrees C in 3 hours. Furthermore, the energy of activation (E-a) was 67.4 kJ.mo1(-1) and the pre-exponential factor (k(o)) was 8.35 x 10(4) L mol(-1) min(-1) determined using Arrhenius equation.