The High Velocity Air Fuel (HVAF) Spray process is becoming more and more popular but despite off its long history, the industrial activities to work out differences of HVAF and classical Kerosene-fired High Velocity Oxygen Fuel (KF-HVOF) Spraying are still on a level of “collecting experience” and “not being understood completely”. This publication gives an explanation of the differences between HVAF and HVOF and their impact on the metallurgy and coating properties.