Oudemans was born in Amsterdam, the oldest of seven children of his namesake teacher father and Jacoba Adriana Hammecker.
A younger brother, Jean Abraham Chrétien became an astronomer and a nephew, Anthonie Cornelis, became a zoologist.
Oudemans went to school in Weltevreden, Java, where his father taught and moved back to Amsterdam for classical studies.
Oudemans distributed two exsiccata-like series Herbarium Nederlandsche planten door C. A. J.
[1][2][3] He retired in 1896 but continued to describe the European parasitic fungi which was published posthumously as Enumeratio systematica fungorum by professor J. W. Moll of Groningen University.