The firm of Hooven, Owens, Rentschler, and Company manufactured steam and diesel engines in Hamilton, Ohio. Because the firm was frequently known by its initials, H.O.R., the Hooven is sometimes incorrectly rendered as Hoover, and the Owens may be mistaken for Owen.

The firm was the successor to the firm of Owens, Ebert & Dyer (founded in 1845 by Job E. Owens) which went into receivership in 1876.

In 1882, George A. Rentschler, J. C. Hooven, Henry C. Sohn, George H. Helvey, and James E. Campbell merged the firm with the iron works of Sohn and Rentschler, and adopted the name Hooven, Owens, Rentschler Co.

In 1883 the firm began the manufacture of Corliss steam engines, producing a total of 700 such engines by 1901.

By World War I, the Hooven-Owens-Rentschler Company operated the largest exclusive Corliss Engine plant in the country, employing nearly 800 men.

Also built were a number of triple expansion engines for the merchant fleet being built under the United States Shipping Board program. The engines had diameters of 27-45-71 inches and a stroke of 48 inches (556nhp - 562nhp).

Diameters of 27.5-46-78 and a stroke of 51 inches (680nhp)

Diameters of 24.5-41.5-72 and a stroke of 48 inches (359nhp), vertical inverted direct-acting, Stephenson-link valve gear, piston travel 700 feet per minute, 88 rpm, intake 200psi, 2800hp