Ret. Lt. Gen. Kökmen was born in Eskişehir, Turkey in 1959. After completing his primary school education in Şafaktepe Primary School (Ankara) and high school education in Sincan High School (Ankara), he joined the Turkish Air Force Academy in 1977. He graduated from the Air Force Academy on August 30, 1981.

Ret. Lt. Gen. Kökmen served in a variety of positions at the squadron and wing levels. Most notably, he has served as the commander of the 182nd Squadron, the wing commander of the 6th Main Jet Base, the base commander of the 8th Main Jet Base, the Chief of Personnel Branch at the Headquarters, the Chief of Plan and Policies at the Headquarters, Deputy Commander of the 1st Air Force Command Headquarter, the Air Defense Commander, and the Air Force Chief of Staff.

Throughout his 38 years of service, Ret. Lt. Gen. Kökmen has logged more than 3900 flying hours including over 200 combat hours with different types of aircrafts (F-16, F-104). He has the NATO Medal, the United Nations Medal, and Turkish Armed Forces Medal of Courage and Self-Sacrifice. He is married to Ayşenur Kökmen, and they have two sons and a grandson (Ege).