In 1954, Oesper received the 5th annual Eminent Chemist award by the American Chemical Society. In 1956 he received the first Dexter Award for Outstanding Achievement in the History of Chemistry from the American Chemical Society. In 1966 he was awarded an honorary doctorate by the University of Cincinnati.
Oesper was a member of the editorial boards of the Journal of Chemical Education, Chymia, Mikrochemie, and Microchimica Acta.
Oesper bequeathed his extensive library to the University of Cincinnati. This included a financial endowment to fund projects on the history of chemistry. The University of Cincinnati with the Cincinnati section of the American Chemical Society present an annual Oesper Award and Symposium series, named in Ralph Oesper's honor.