Uncial 0142 (in the Gregory-Aland numbering), O⁶ (Soden), is a Greek uncial manuscript of the New Testament, dated paleographically to the 10th century. Formerly it was classified as a minuscule manuscript of New Testament under numbers 46^a 55^p (Scrivener).

The codex contains the complete Acts, Catholic epistles, and Pauline epistles, on 381 parchment leaves (32 cm by 24.5 cm). It is written in one column per page, 40 lines per page, in uncial letters, but uncial letters are mixed with minuscule letters. It contains a commentary of Pseudo-Oecumenius.

It contains stichoi.

The Greek text of this codex is a representative of the Byzantine text-type. Aland placed it in Category V. Uncial 056 probably was rewritten from the codex 0142.

It lacks Acts 8:37.

In Acts 18:26 it reads την του θεου οδον along with P, Ψ, 049, 104, 330, 451, 1241, 1877, 2127, 2492, Byz, Lect;

In Acts 20:15 it reads και μειναντες εν Στρογγυλιω along with 056.

Currently it is dated by the INTF to the 10th century.