The official Cambodian language, known in English as Khmer, belongs to the Eastern Mon-Khmer group of the Mon-Khmer language family. Employing a script which (like Thai and Burmese) is believed to have evolved from southern Indian Brahmi, Khmer is one of the few non-tonal languages in South East Asia. Centuries of close contact between Thailand and Cambodia has resulted in a considerable amount of borrowing between the two languages, both at the lexical and syntactical levels.

As in neighbouring Việt Nam and Laos, French and Vietnamese are still spoken by members of the older generation, but the use of English is rapidly becoming widespread throughout the country and is expected to increase because it is the language employed within the Association of South East Asian Nations (ASEAN).