This seminar report discusses gas insulated transformers, which use sulfur hexafluoride (SF6) gas instead of oil as both an insulating and cooling agent. SF6 has excellent dielectric and cooling properties and is nonflammable, nontoxic, and recyclable. Gas insulated transformers are advantageous as they have a smaller footprint, higher reliability, and cause no pollution. They are suitable for applications like hospitals and underground facilities where fire safety is important. The report outlines the features, layout, cooling apparatus, and accessories of gas insulated transformers and concludes that ongoing research is improving their efficiency and making power systems more reliable and safe.