The Mongolian Cyrillic alphabet (Mongolian: Монгол Кирилл үсэг, Mongol Kirill üseg or Mongolian: Кирилл цагаан толгой, Kirill tsagaan tolgoi) is the writing system used for the standard dialect of the Mongolian language in the modern state of Mongolia. It has a largely phonemic orthography, meaning that there is a fair degree of consistency in the representation of individual sounds. Cyrillic has not been adopted as the writing system in the Inner Mongolia region of China, which continues to use the traditional Mongolian script.
Mongolian Cyrillic is the most recent of the many writing systems that have been used for Mongolian. It is a Cyrillic alphabet and is thus similar to, for example, the Bulgarian alphabet, and identical to the Russian alphabet except for the two additional characters Өө ⟨ö⟩ and Үү ⟨ü⟩.
It was introduced in the 1940s in the Mongolian People's Republic under Soviet influence, after a brief period where Latin was used as the official script. After the Mongolian democratic revolution in 1990, the traditional Mongolian script was briefly considered to replace Cyrillic, but this has not come to fruition. Nevertheless, the Mongolian script has become a compulsory subject in primary and secondary schooling and is slowly gaining in popularity. The Mongolian script is a highly unusual vertical script, and unlike scripts such as the Chinese script, it cannot easily be adapted for horizontal use, which puts it at a disadvantage compared to Cyrillic for many modern purposes. Thus, the Cyrillic script continues to be used in everyday life and on the Internet.