Abstract: The pesticidal composition of the invention comprises dichlorvos and chlorpyrifos. The composition is prepared by combining the components together and then subjecting the mixture to microwave radiation. The resultant composition exhibits a synergistic effect on the individual properties of the respective components which not only quickly exterminates existing pests but which also leaves a residual pesticidal protection which is not readily removed by conventional cleaning processes. The composition is particularly effective against cockroaches.