[1] Fittig studied chemistry at the University of Göttingen, graduating as Ph.D. with a dissertation on acetone in 1858, under the supervision of Heinrich Limpricht and Friedrich Wöhler.

[citation needed] He subsequently held several appointments at Göttingen, becoming Wöhler's assistant in 1858, privatdozent in 1860 and extraordinary professor in 1870.

Fittig and Erdmann's observation that γ-phenyl structural analog of isocrotonic acid readily yielded α-naphthol by loss of water was of much importance, since it afforded valuable evidence as to the constitution of naphthalene.

[16] They also investigated certain hydrocarbons occurring in the high boiling point fraction of the coal tar distillate and solved the constitution of phenanthrene.

Much initial knowledge of the alkaloid piperine was owed to Fittig, who in collaboration with Ira Remsen established its constitution in 1871.