[2] Oudney has been described as quiet, self-effacing, and a short man with a weak constitution particularly unsuited to the rigors of African exploration.
With the intention of discovering if the Niger River flowed into Lake Chad or continued further east possibly merging with the Nile.
[3] In early 1822, he departed from Tripoli with explorers Dixon Denham (1786–1828) and Hugh Clapperton (1788–1827), reaching Bornu in February 1823, and thus becoming the first Europeans to accomplish a north–south crossing of the Sahara Desert.
[4] On the journey he collected regional plants, and after his death Scottish botanist Robert Brown (1773–1858) named the botanical genus Oudneya from the family Brassicaceae in his honor.
In 1826 the two-volume "Narrative of Travels and Discoveries in Northern and Central Africa in the years 1822, 1823, and 1824" was published, describing the African exploits of Oudney, Denham and Clapperton.