The year 1880 in science and technology included many events, some of which are listed here.

• September 30 – American doctor Henry Draper takes the first photograph of the Orion Nebula, from Hastings-on-Hudson, New York; this year he also photographs the spectrum of Jupiter.

• F. Landry finds the largest known Fermat prime, 65537.
• John Venn popularises Venn diagrams.^[1][2]

• Moritz Kaposi publishes Pathologie und Therapie der Hautkrankheiten in Vorlesungen für praktische Ärzte und Studierende ("Pathology and treatment of diseases of the skin, for practitioners and students"), a significant textbook in dermatology.^[3]
• German professor of pathology Karl Eberth first visualizes the bacteria which will become known as Salmonella in the Peyer's patches and spleens of typhoid patients.^[4]
• English surgeon Sampson Gamgee reports on his use of the medical dressing Gamgee Tissue.^[5]
• Scottish surgeon William Macewen reports on his use of orotracheal intubation as an alternative to tracheotomy.^[6]

• February 13 – Thomas Edison observes the Edison effect.
• The first demonstration of the direct piezoelectric effect is made by the brothers Pierre Curie and Jacques Curie.^[7]
• Johannes Diderik van der Waals formulates the Law of Corresponding States.

• February 19 – The photophone, an optical speech transmission system, is invented by Alexander Graham Bell and Charles Sumner Tainter in Washington, D.C.
• Dugald Clerk builds the first successful two-stroke engine.^[8]

• February – The journal Science is first published in the United States with financial backing from Thomas Edison.
• Start of publication of Report Of The Scientific Results of the Exploring Voyage of H.M.S. Challenger during the years 1873-76.

• Copley Medal: James Joseph Sylvester^[9]
• Wollaston Medal: Auguste Daubrée

• January 18 – Paul Ehrenfest (died 1933), Austrian physicist and mathematician.
• January 22 – Frigyes Riesz (died 1956), Hungarian mathematician.
• February 17 – Reginald Farrer (died 1920), English botanist.
• June 21 – Arnold Gesell (died 1961), American developmental psychologist.
• June 24 – Oswald Veblen (died 1960), American mathematician.
• August 17 – Paul Kammerer (died 1926), Austrian Lamarckian biologist.
• October 15 – Marie Stopes (died 1958), English paleobotanist and pioneer of birth control.

• January 9 – William Budd (born 1811), English physician and epidemiologist.
• May 6 – Friedrich Bayer (born 1825), German manufacturing chemist.
• July 9 – Paul Broca (born 1824), French anthropologist.
• October 5 – William Lassell (born 1799), English astronomer (died 1880)
• December 31
  • Eric Holmes (born 1821), British chemist.
  • John Stenhouse (born 1809), Scottish chemist.