In this study, transesterification of low quality crude jatropha oil (acid value 7.54 mg KOH/g oil & water content 223 ppm) to biodiesel using modified natural dolomite as a solid catalyst was carried out. The effects of various factors consist of the reaction time, water resistance, FFA resistance and catalyst reusability was investigated. The calcined natural dolomite was synthesized in two different ways by refluxing in distilled water and methanol to increase the activity and improve the properties of calcined natural dolomite in order to make it highly suitable for biodiesel production. The water treatment technique yielded solid CaMgO_W with a surface area about twice that of the CaMgO_S, achieved an excellent performance of 97.4 wt.% methyl ester content within 2 h and showed a high tolerance to the water content (mass fraction 0.0523%) and the fatty acid content (mass fraction 4.77%). The catalyst was reused two times and still maintained the methyl ester content over 97.4 wt%. Although the dolomite has a limited reusability in biodiesel production reaction, the cost and availability make it an acceptable alternative.