A multitude of synthetic routes are available for the preparation of sulfonyl fluorides (R-SO2F) whose discovery is now almost a century old. These syntheses are often limited by the scope, hazardous materials, and elaborate procedures. The simple and mild procedure based on direct chloride/fluoride exchange from a sulfonyl chloride (R-SO2Cl) starting material in a KF and water/acetone biphasic mixture is investigated. Seventeen examples in high yield (84-100%) with wide scope are described.