This review discusses the antimicrobial activity of titanium dioxide (TiO₂) as a photocatalyst for disinfection of surfaces, air, and water. TiO₂ is a semiconductor that generates reactive oxygen species (ROS), such as hydroxyl radicals and hydrogen peroxide, when exposed to light. These species can degrade the cell walls and membranes of microorganisms, leading to cell death. The effectiveness of TiO₂ depends on the type of microorganism, the wavelength of light, and the presence of other antimicrobial agents like copper and silver. Gram-negative bacteria are generally more susceptible to TiO₂ than Gram-positive bacteria, although some Gram-positive bacteria are more sensitive. Fungi, algae, protozoa, and viruses are also susceptible to TiO₂ photocatalytic action. The killing mechanism involves the degradation of cell walls and membranes, leading to leakage of cellular contents and eventual cell lysis. The efficiency of TiO₂ is enhanced when there is close contact between the microorganisms and the catalyst. The use of visible light-activated TiO₂ has been explored to improve the efficiency of photocatalytic disinfection. The review also highlights the potential of TiO₂ for the complete mineralisation of microorganisms, and the importance of contact between bacteria and TiO₂ for effective disinfection. The role of ROS in the killing mechanism is discussed, as well as the effects of different factors such as ionic species and surface area on the efficiency of TiO₂ photocatalytic disinfection. The review concludes that TiO₂ has significant potential for use in disinfection applications, particularly with the development of visible light-activated catalysts.This review discusses the antimicrobial activity of titanium dioxide (TiO₂) as a photocatalyst for disinfection of surfaces, air, and water. TiO₂ is a semiconductor that generates reactive oxygen species (ROS), such as hydroxyl radicals and hydrogen peroxide, when exposed to light. These species can degrade the cell walls and membranes of microorganisms, leading to cell death. The effectiveness of TiO₂ depends on the type of microorganism, the wavelength of light, and the presence of other antimicrobial agents like copper and silver. Gram-negative bacteria are generally more susceptible to TiO₂ than Gram-positive bacteria, although some Gram-positive bacteria are more sensitive. Fungi, algae, protozoa, and viruses are also susceptible to TiO₂ photocatalytic action. The killing mechanism involves the degradation of cell walls and membranes, leading to leakage of cellular contents and eventual cell lysis. The efficiency of TiO₂ is enhanced when there is close contact between the microorganisms and the catalyst. The use of visible light-activated TiO₂ has been explored to improve the efficiency of photocatalytic disinfection. The review also highlights the potential of TiO₂ for the complete mineralisation of microorganisms, and the importance of contact between bacteria and TiO₂ for effective disinfection. The role of ROS in the killing mechanism is discussed, as well as the effects of different factors such as ionic species and surface area on the efficiency of TiO₂ photocatalytic disinfection. The review concludes that TiO₂ has significant potential for use in disinfection applications, particularly with the development of visible light-activated catalysts.