HFO-1234yf (R-1234yf), marketed as Honeywell Solstice® yf, is a modern hydrofluoroolefin (HFO) refrigerant primarily designed for automotive air-conditioning systems. It boasts an ultra-low Global Warming Potential (GWP) of less than 1 and zero Ozone Depletion Potential (ODP), significantly minimizing climate impact and supporting global regulatory trends for low-GWP refrigerants. Classified as ASHRAE A2L (mildly flammable), it offers thermodynamic properties and cooling performance similar to R-134a, allowing for its replacement with only minor system modifications and compatibility with POE lubricants. This refrigerant is widely adopted by automotive OEMs for new passenger cars, hybrid/electric vehicles, and aftermarket servicing. While mildly flammable, its safe use in automotive systems is ensured with correct management, requiring proper handling, adequate ventilation, and the elimination of ignition sources during maintenance and servicing.