| Industry: | Engineering |
| Fate: | Acquired by ABB Transportation |
| Foundation: | 1921 |
| Defunct: | 1990 |
| Location City: | Granville |
| Locations: | Dandenong Rocklea Bassendean |
| Products: | Railway rolling stock |
| Parent: | Australian National Industries |
Commonwealth Engineering (often shortened to Com-Eng, later Comeng [{{IPAc-en|ˈ|k|ɒ|m|ɛ|n|dʒ}} {{respell|KOM|enj}}]) was an Australian engineering company that designed and built railway locomotives, rolling stock and trams.
Smith and Waddington, the predecessor to Commonwealth Engineering, was founded in 1921, in the Sydney suburb of Camperdown, as a body builder for custom motor cars. It went bankrupt in the Depression, and was reformed as Waddingtons Body Works and the main factory was moved to Granville, after a fire in the main workshop. The Government of Australia took control of the company during World War II as the company was in serious financial difficulties but had many government orders in its books. The government purchased a controlling stake in the company in 1946 and changed the name to Commonwealth Engineering.
In 1949 a factory was established in Rocklea, Queensland. This was followed in 1952 by a plant in Bassendean, Western Australia and in 1954 by another in Dandenong, Victoria. In June 1957, the government sold its shares. In November 1982 Comeng was taken over by Australian National Industries.
The Granville factory closed in 1989 and has been demolished. The site, which was situated between the Great Western Highway and Main Western railway line west of Duck River, has been replaced with new developments including high-rise housing and light industries.
In 1990, the Dandenong plant was sold to ABB (later Bombardier Transportation, now Alstom), while the Bassendean facility was sold to A Goninan & Co.
John Dunn has written a history of Comeng:
Leyland OPSU1/1s