This study examined suitable areas for growing Jatropha plants and focused on the improvement of Jatropha oil as an alternative fuel for diesel engine. To examine land suitability for Jatropha cultivation, this study examined case studies in Suphanburi province, Thailand by classifying land use from landsat-5 TM. Then, GIS based spatial multiple criteria decision-making analysis was used to identify suitable land for Jatropha cultivation. Analytical Hierarchical Processing (AHP) was used to weight multi-factor priority model for land suitability for Jatropha cultivation. The results were obtained that the marginally suitable area for Jatropha cultivation in Suphanburi is 3,569.02 sq.km and 1,577.70 sq.km. and 211.29 sq.km. for highly suitable and moderately suitabille area respectively. The results found that viscosity of 5- 10% of Jatropha blends can be acceptable according to the ASTM standard. For using Jatropha oil (pure), the fuel should be heat more than 100 Celsius before directly used in engine. The study revealed that blending with 5-10% of Jatropha oil can be used directly in diesel engine without any modification or preheating.