Jesse Francis McClendon (December 21, 1880 – November 22, 1976) was an American chemist, zoologist, and physiologist known for the first pH measurement of human stomach in situ. Jesse F. McClendon made substantial contributions in a variety of fields, including invertebrate zoology, nutrition, life processes of cell membranes, the importance of pH control, the role of iodine in human health, and specifically its relation to prevention of goiters.