, abbreviated to , was a public university in Japan. It was located in Sumiyoshi-ku, Osaka. The university merged with Osaka Prefecture University to form Osaka Metropolitan University in April 2022.
OCU's predecessor was founded in 1880, as with donations by local merchants. It became Osaka Commercial School in 1885, then was municipalized in 1889. Osaka City was defeated in a bid to draw the Second National Commercial College (the winner was Kobe City), so the city authorities decided to establish a municipal commercial college without any aid from the national budget. In 1928, the college became , the first municipal university in Japan.
In 1901, the school was reorganized to become , later authorized under Specialized School Order in 1904. The college had grand brick buildings around the Taishà  period.
In 1949 OCU had five faculties (Business / Economics / Law and Literature / Science and Engineering / Home Economics).<br /> In 1953, the Faculty of Law and Literature was divided into two faculties.<br /> In 1955, Osaka City Medical University was incorporated and became the Faculty of Medicine.<br /> In 1959, the Faculty of Science and Engineering was divided into two faculties.<br /> In 1975, the Faculty of Home Economics was reorganized into the Faculty of Human Life Science.<br /> In 2003, the Graduate School of Creative Cities was established.<br /> In 2006, the Urban Research Plaza and the Advanced Research Institute for Natural Science and Technology were established.<br /> Due to financial problems in many cities, all of the municipal universities in Japan were requested to incorporate. OCU became a Public University Corporation in 2006.<br /> In 2015 OCU celebrated its 135th anniversary. In June 2020, OCU announced it would be merging with Osaka Prefecture University in a new university named University of Osaka. However, after the name was announced on June 26, 2020, Osaka University President released a statement pointing out that the English version of the new university's name was "remarkably similar" to that of Osaka University, adding, "It will cause confusion among our students, and work as a great obstacle for the future of both universities, which are reaching out to the world." The English name ultimately chosen was Osaka Metropolitan University.