Bis(tributyltin) oxide (TBTO) is primarily used as a biocide in antifouling paints applied to ship hulls, docks, and other marine structures to prevent the growth of barnacles, algae, and other marine organisms. This helps maintain vessel efficiency by reducing drag and fuel consumption. It is also employed in wood preservation to protect against fungi, termites, and other pests, extending the lifespan of treated wood in outdoor applications. Additionally, TBTO has been used in cooling water systems to control microbial growth. However, due to its high toxicity to marine life and environmental persistence, its use has been restricted or banned in many regions.