Hong Kong written Chinese (HKWC)^[1] is a local variety of written Chinese used in formal written communication in Hong Kong.^[2] The common Hongkongese name for this form of Chinese is "written language" (書面語), in contrast to the "spoken language" (口語), i.e. Cantonese.^[3] While, like other varieties of Written Chinese, it is largely based on Mandarin, it differs from the mainland’s national variety of Standard Chinese (Putonghua) in several aspects, for example that it is written in traditional characters, that its phonology is based on Cantonese, and that its lexicon has English and Cantonese influences.^[4] Thus it must not be confused with written Cantonese which, even in Hong Kong, enjoys much less prestige as a literary language than the "written language".^{[citation needed]} The language situation in Hong Kong still reflects the pre-20th century situation of Chinese diglossia where the spoken and literary language differed and the latter was read aloud in the phonology of the respective regional variety instead of a national one.

With the establishment of Modern Standard Chinese in the Republic of China teaching materials began to be exported into the British Crown Colonies Hong Kong, Singapore and Malaya. The victory of the Communists over the nationalist Kuomintang in the Chinese Civil War, the retreat of the Republican government to the island of Taiwan, and the subsequent diplomatic isolation of the People's Republic of China under the One-China policy led to a diversification of the Standard Chinese language, so that there are four varieties of more strongly standardized Chinese today: Putonghua in Mainland China, Guoyu on Taiwan, and Huayu in Singapore and Malaysia. Hong Kong on the other hand was a British colony until 1997 and for most of the colonial era English had been the only official language. Chinese was only recognized as a co-official language in 1974 after recurring riots as well as scholarly activism. And although legal texts were translated from English into Chinese in the late 1970s the English versions alone continued to be the ultimately valid ones. This meant that there was not much historical effort on the British side to standardize Chinese in Hong Kong. This lack of political intervention facilitated the formation what was coined Hong Kong style Chinese (港式中文, translated as Hong Kong written Chinese by Shi, 2006^[2]) by linguist Shao Jingmin in 1996 in order to distinguish it from Putonghua.

The grammar of the Hong Kong written Chinese is largely based on Mandarin Chinese, while its phonology is based on Cantonese. Yet one distinguishes between colloquial and literary readings of Chinese characters. The latter are based on traditional rime dictionaries and employed when reading out loud texts in Classical or modern written Chinese. Thus students in Hong Kong schools get corrected by their teachers when reading aloud HKWC texts in the colloquial pronunciation.^[3] Some regular differences between colloquial and literary readings in Cantonese are:

1. The Late Middle Chinese (LMC) initial */fɦ-/ corresponds to colloquial /p-/ and /pʰ-/, but to literary /f-/, e.g. 婦 LMC */fɦuə̌/, coll. /pʰou˩˧/, and lit. /fu˩˧/, '(married) woman'.
2. The LMC syllables /ŋiC_nasal/ and /ŋi̯eC_nasal/ correspond to colloquial /ŋɐC_nasal/ and /ŋa:C_nasal/ respectively, but to literary /jɐC_nasal/ and /jiC_nasal/, e.g. 吟 LMC /ŋīm/, coll. /ŋɐm˨˩/, and lit. /jɐm˨˩/ 'to recite; to groan'; 研 LMC /ŋi̯ên/, coll. /ŋaːn˨˩/, and lit. /jin˨˩/ 'research'.
3. The colloquial rimes /-ɛːC/ and /-ɛːu̯/ correspond to literary rimes /-ɪC/ and /-iːu̯/ respectively, e.g. 名 coll. /mɛːŋ˨˩/ versus lit. /mɪŋ˨˩/, 'name'.
4. The colloquial rime /-ɐɪ̯/ corresponds to literary /-ɔɪ̯/ when going back to LMC */-ʌi/, whereas it corresponds to literary /-iː/ when going back to LMC */-i/.
5. The colloquial rime /-œː/ corresponds to literary /-ɔː/.
6. LMC syllables with voiced/breathy obstruent initials and rising-tone rimes correspond to colloquial readings with aspirate initials and low-rising-tone rimes, but to literary readings with tenuis initials and low-even-tone rimes, e.g. 棒 LMC /pɦə̌ŋ/, coll. /pʰaːŋ˩˧/, and lit. /paːŋ˨/. Here the colloquial variant preserves the phonetic realization of the LMC tone more authentically. The literary reading imitates the correspondence of LMC syllables with voiced obstruent initials and rising-tone rimes with Mandarin syllables with falling-tone rimes (the Cantonese mid- and lower-even tone rimes correspond to Mandarin falling-tone rimes).

When written, HKWC generally differs almost as much from written Cantonese as Standard Chinese does. Some examples: