<div><p><em>The inhibition efficiency of DMBP (Diethyl-4-methyl benzyl phosphonate) along with Biocidal action of CTAB and SDS on corrosion of mild steel in neutral aqueous medium has been evaluated by mass loss method, both in absence and presence of Zn<sup>2+</sup>. It is observed that DMBP exhibits 65% IE individually at ambient temperature. Synergistic influence of Zn<sup>2+</sup> increases IE of DMBP to 71%. Addition of surfactants CTAB (N-Cetyl-N,N,N-Trimethyl Ammonium Bromide) and SDS ( Sodium dodecyl Benzene sulphonate) enhances the inhibition efficiency of DMBP from 65% to 96% and 92% respectively. The inhibitor system consisting of DMBP (200 ppm) + Zn<sup>2+</sup> (90 ppm)+ CTAB (50 ppm) / SDS (40 ppm) offered maximum Biocidal efficiency (BE %) of 100% after killing of microbial bacteria present in aqueous system. FTIR spectra indicates the protective film consist of Fe<sup>2+</sup>-DMBP and Zn(OH)<sub>2</sub>.</em></p></div>