RATIONALE: Benzene (C ₆H ₆) is industrially important aromatic molecule which used as a primary reagent in pharmaceutical and petrochemical industries and on the other hand in the preparation of polystyrene for plastic industries, styrene (C ₈H ₈) is used as monomer. This motivated us to carry out the extensive study for the considered molecules. METHODS: The single differential cross-sections and their integral i.e. total ionization cross-sections for benzene and styrene molecules have been calculated by employing modified Jain-Khare semiempirical formulation. The ionization rate coefficient is calculated by using Maxwell-Boltzmann distribution law of temperature/energy. To confirm the consistency and reliability of the calculated ionization Qion data and, to prove the reliability of the employed JK formulation we used the empirical relationship reported by Lampe, Franklin and field. RESULTS: The secondary electron energy dependent differential cross sections at fix incident electron energies 100 and 200 eV and their integral cross-sections from ionization threshold to 5 keV have been calculated. The averaged secondary electron energy and the rate coefficients in ionization threshold to 5 keV energy range are also calculated and we found the linear relationship between Q _ion and (⍺/I) ^1/2, which confirm the consistency and reliability of the present data and applied JK formulation. CONCLUSION: The present TICS are found to be in good agreement with theoretical and experimental available data sets and are significant for the pharmaceutical and petrochemical industries, the planetary atmosphere, the plastic industries, and X-ray lithography techniques in microelectronics and microfabrication. This encourages the atomic and molecular communities for better outcomes.