Silver nanoparticles of particle size around 15 nm were synthesized by following a simple and green methodology of photoreduction of silver nitrate (AgNO3) using bare titania and polyvinyl alcohol (PVA)-capped colloidal titanium dioxide nanoparticles/nanotubes under UV−vis light (λ = 365 nm). The synthesized pure TiO2 nanoparticles/tubes, Ag−TiO2 nanocomposites and PVA-capped colloidal Ag−TiO2 nanocomposites are characterized for their structure and morphology by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and for their electronic structure by X-ray photoelectron spectroscopy (XPS). The antibacterial efficiency of all nanocomposites were investigated on Escherichia coli using standard procedures. The synthesized metal−metal oxide nanocomposites are shown to be very efficient toward destroying Gram negative bacteria Escherichia coli.