Khon Kaen (Thai: ขอนแก่น, pronounced [kʰɔ̌ːn kɛ̀n] or  [kʰɔ̌n kɛ̀n]) is one of the four major cities of Isan, Thailand, also known as the "Big 4 of Isan", the others being Udon Thani, Khorat, and Ubon Ratchathani. It is also the capital of Khon Kaen Province and the Khon Kaen District.

Thailand's 2014 EU Film Festival included Khon Kaen, together with Chiang Mai and Bangkok, as host locations. A selection of six films was shown in the city, including the Spanish film The Pelayos and the Polish film Walesa, Man of Hope.

Khon Kaen's climate is categorized as tropical savanna (Köppen climate classification Aw), with winters that are dry and very warm. Temperatures rise until April, a very hot month, with an average daily maximum of 36.3 °C (97.3 °F). The monsoon season runs from May until October, with heavy rain and somewhat cooler temperatures during the day, although nights remain warm.