Buchner, the brother of Eduard Buchner, was born in Munich, Germany, and gained his MD from the University of Leipzig in 1874. He later worked at Munich University serving as professor of hygiene from 1894 until his death.

In 1888 George Nuttall had shown that the ability of blood to destroy invading bacteria lay in the serum. Buchner followed up his work and went on to demonstrate that the bacteriolytic power was lost when the serum was heated to 56°C. He therefore concluded that serum possessed a heat labile substance that he proposed to name alexin.

This work was soon extended by Jules Bordet and the alexins were later renamed ‘complement’ by Paul Ehrlich. Buchner also did basic work on gamma globulins and developed techniques to study anaerobic bacteria.