The formation of bacterial biofilms on medical implants is a well-documented problem in healthcare settings. Infections mediated by biofilm phases are particularly challenging to resolve, owing to their high tolerance toward antimicrobials. The social and economic impact of these infections is particularly evident in the field of orthopaedics, where bacterial biofilms contribute significantly to revision surgery. In consideration of the emergence of antibiotic resistance, and increased use of orthopaedic implants, it is critical that efforts are made to find alternative approaches to tackle biofilm formation. A possible solution could be found in the design of surface topographies with bactericidal properties. Natural surfaces, including the Cicada and Dragonfly wing, have evolved nanostructures that kill bacteria upon attachment; this bactericidal mechanism is believed to be mediated through physical rupture of the cell membrane. In this study, a thermal oxidation technique was employed to generate bactericidal TiO2 nanostructures (NS) on medical grade titanium alloy (Ti-6Al-4V). To advance our understanding of this contact killing mechanism, the Gram negative pathogen Klebsiella pneumoniae was incubated on these TiO2 surfaces. A combination of bacterial viability assays and electron microscopy techniques were used to investigate the integrity of bacterial cells. Electron microscope observations found that TiO2 NS disrupt the membrane of K. pneumoniae, causing the cells to rupture and deform. In certain cases the TiO2 NS were seen to entirely penetrate the bacterial cell, indicating that both the cell wall and membrane had been compromised. Supporting these findings, Live/Dead BacLight viability staining revealed significantly higher levels of killing on TiO2 NS surfaces compared to smooth Ti-6Al-4V controls. These results illustrate the potential of thermal oxidation as a novel approach to generating bactericidal nanotopographies on titanium. The ability of these surfaces to physically rupture and kill K. pneumoniae upon attachment could prove an invaluable alternative to chemical methods that are prone to bacterial resistance. These surfaces provide a promising start point from which the bactericidal activity can be systematically enhanced.