Vegetable oil is proved as a valuable feedstock in biofuel production. Some common issues of vegetable oil cracking –as an effective method for biofuel production- related to glycerol decomposition during cracking. Transesterification, which can remove glycerol from vegetable oil molecule, was performed before thermal cracking to adjust the problems. This study was aimed at surveying the efficiency of transesterification and thermal cracking integration to produce bio-gasoline and bio-oil from castor oil. In transesterification, methanol as alcohol and KOH as catalyst were used, and catalyst concentration, reaction temperature, and alcohol to oil ratio were effective variables. Statistical studies demonstrated the interactions among parameters and yield of methyl ester production was 96.7% in the optimized conditions. Results showed that in the thermal cracking, two parameters of feed flowrate and temperature, influence products yield significantly without any interaction. At the optimum conditions to maximize bio-gasoline production, 28% bio-gasoline and 88.6% bio-oil were achieved. The lack of acrolein production as a toxic component, the negligible generated water in the product, high octane number, significant combustion heat of bio-gasoline, and being in criteria of standard gasoline by ASTM D4814 for distillation curve and RVP of bio-gasoline, all were the great advantages of transesterified castor oil cracking. Therefore, bio-gasoline produced via thermochemical conversion of castor oil could be used as a fuel of spark-ignition engines or as an octane enhancer with gasoline, i.e., by adding 10% of bio-gasoline to the refinery gasoline, the octane number increased from 95 to 105.