Acrylamide/4-vinyl pyridine hydrogels were synthesized by radiation polymerization technique using a -irradiator. The prepared radiation-synthesized acrylamide/4-vinyl pyridine hydrogels were then treated using a modifying agent with aromatic functional group. The modifying agent used in the modification of acrylamide/4-vinyl pyridine hydrogels was the N-aromatic alkyl quaternizing agent of chloromethyl benzene. The functional group on the modified acrylamide/4-vinyl pyridine hydrogels was confirmed with Fourier transform infrared (FTIR) spectrometry. Thermal analysis, surface morphology investigation, and swelling of the modified and unmodified hydrogels were completed. The antibacterial and antifungal activities of the modified and unmodified hydrogels were also tested against gram-positive Staphylococcus aureus (ATCC 25923); two gram-negative Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853) human pathogenic bacteria and a fungal strainCandida albicans (ATCC 10231) for their MBC values. It was found that acrylamide/4-vinyl pyridine hydrogels do not possess biocidal properties, whereas the modified form of acrylamide/4-vinyl pyridine-chloromethyl benzene showed highly bactericidal characteristics.