Gama-A1203 and KNO3/gama-Al2O3, materials have been successfully synthesized. The properties of materials were investigated by IR, XRD, SEM. The catalytic activity of KNO3/gama-Al2O3 was assessed by transesterification from jatropha oil with methanol. The experimental results showed that the KNO3/gama-Al2O3 catalyst favours the production of fatty acid methylester. The obtained characterization by IR, GC-MS and the quality assessment by ASTM showed that biodiesel from jatropha oil have good properties as commercial biodiesel.