The insecticidal potential of Jatropha curcas seed oil against Callosobruchus maculatus on stored cowpea was evaluated under laboratory condition. The seed oil was applied at concentrations of 0.2, 0.3, 0.5, and 1.0ml/50g of cowpea seeds. An untreated control and solvent (petroleum spirit)-containing treatment were also included. Jatropha seed oil was highly toxic to cowpea bruchids at all selected dosages compared to the untreated control and solvent treatment. Results showed that adult mortality of bruchids at the highest concentration of 1.0ml/50g seeds gave 100%while the lowest concentration gave 93% mortality. The oil was also significantly (p