On 10 August 1897 Hoffmann synthesized acetylsalicylic acid (ASA) while working at Bayer under Arthur Eichengrün.
Hoffmann first claimed to be the inventor of aspirin (as opposed to just the synthesizer) in a footnote to a German encyclopedia published in 1934, saying that his father had complained about the bitter taste of sodium salicylate, the only drug then available to treat rheumatism.