A novel series of Substituted Erythromycin derivatives (5-7) were synthesized by methylation of substituted S-MOP (4) The structures of the synthesized compounds were established by IR, 1H NMR, 13C NMR and Mass spectroscopical data. All the synthesized compounds were screened for their in-vitro antibacterial activity against Gram-positive, Gram-negative bacteria. The investigation of antibacterial screening data revealed that most of the compounds tested have demonstrated congruent activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Klebsiella as compared with the standard Erythromycin. Among the series, compounds 7 exhibited excellent an antibacterial activity profile as compared with the standard. In summary, preliminary results indicate that some of the newly synthesized title compounds exhibited promising antibacterial activities and they warrant more consideration as prospective antimicrobials.