Undoped, Co doped and Co + F doped ZnO nanopowders were synthesized using a simple soft chemical method and certain physical and antibacterial properties of the samples were studied and reported. The XRD patterns reveal that the samples has hexagonal wurtzite structure with preferential orientation along (101) plane. Reduction in grain size caused by Co and Co + F doping is observed from FESEM images. The observed photoluminescence peaks related to the defects confirmed the incorporation of Co, Co + F into the ZnO lattice. Co + F doped ZnO nanopowder exhibits higher antibacterial activity than undoped and Co doped ZnO nanopowders against all the four different bacteria tested in this study viz. B. subtilis, S. aureus, E. coli and P. aeruginosa. The enhanced antibacterial activity of doubly doped ZnO nanopowder is mainly due to the generation of hydroxyl radicals (OH−) in the system.