Nong Khai (Thai: หนองคาย, pronounced [nɔ̌ːŋ kʰāːj]) is the northernmost of the northeastern (Isan) provinces (changwat) of Thailand. Neighbouring provinces are (from east clockwise) Bueng Kan, Sakon Nakhon, Udon Thani, and Loei. To the north it borders Vientiane Province, Vientiane Prefecture, and Bolikhamxai of Laos.