We have carried out a joint experimental and theoretical study on determination of total and elastic cross-sections for electron and positron impact on OCS molecules. For total cross-section measurements, impact energies are from 0.7 to 600 eV for electron collisions and 0.8 to 600 eV for positron collisions. For elastic scattering, only electron impact has been studied from 1.5 to 100 eV. Our present measurements for total cross-sections for electron impact are found to agree extremely well with the measurements of Dababneh et al. (1982) in the entire energy region studied. The results by Szmytkowski et al. (1994) are consistently larger by 20% above 2 eV, and, in particular, are larger by a factor of two in the 1.2 eV resonance region. The present theory for elastic scattering is in good agreement with the present measurement, and has been employed for understanding the dynamics. The total cross-section recommended here is probably the best in accuracy as of today although further studies would be helpful.