| Julius Arnold Koch | |
| Birth Date: | 1864 8, df=y |
| Birth Place: | Free Hanseatic City of Bremen |
| Nationality: | German American |
| Death Place: | Pittsburgh, United States |
| Work Institution: | University of Pittsburgh |
| Known For: | Gattermann-Koch reaction |
Julius Arnold Koch (August 15, 1864 – February 2, 1956) was an American chemist who was born in the Free Hanseatic City of Bremen. Koch graduated from the University of Pittsburgh in 1884. He was the first dean of the University of Pittsburgh School of Pharmacy and held this position until his 1932 retirement. In 1897, he discovered, together with Ludwig Gattermann, the Gattermann-Koch reactiona method of synthesis of benzaldehyde using carbon monoxide.[1] He agreed to accept the status of dean only if the school's "sessions [were] changed from evening to the daytime."[2]