The year 1833 in science and technology involved some significant events, listed below.

• November 12–13 – A spectacular occurrence of the Leonid meteor shower is observed over Alabama.

• May 3 – The Entomological Society of London is inaugurated.
• Katherine Sophia Kane's The Irish Flora is published anonymously.

• Thomas Graham proposes Graham's Law.

• June 5 – Ada Lovelace is introduced to Charles Babbage by Mary Somerville.^[1]

• November 25 – A major 8.7 earthquake strikes Sumatra.

• probable date – Paul Gerwien proves the Bolyai–Gerwien theorem formulated by Farkas Bolyai: that any two simple polygons of equal area are equidecomposable.

• Henry Witham publishes The Internal Structure of Fossil Vegetables found in the Carboniferous and Oolitic deposits of Great Britain in Edinburgh.

• Carl Friedrich Gauss and Wilhelm Eduard Weber develop an electromagnetic telegraph at Göttingen.

• William Beaumont publishes Experiments and Observations on the Gastric Juice and the Physiology of Digestion.
• Charles Bell publishes The Hand: its Mechanism and Vital Endowments as Evincing Design, the fourth Bridgewater Treatise.
• Marshall Hall coins the term "reflex" for a muscular reaction.
• Jean Lobstein proposes use of the term arteriosclerosis.^[2]
• Johannes Peter Müller begins publication of his major physiology textbook Handbuch der Physiologie des Menschen.
• Anselme Payen discovers diastase (the first enzyme identified).

• August 18 – The Canadian ship SS Royal William sets out from Pictou, Nova Scotia on a 25-day passage of the Atlantic Ocean largely under steam to Gravesend, Kent, England.
• Obed Hussey patents a reaper in the United States.^[3][4]
• Cornish engineer Adrian Stephens invents the steam whistle as a warning device at Dowlais Ironworks in Wales.^[5][6]
• Publication by Charles Knight of The Penny Cyclopædia of the Society for the Diffusion of Useful Knowledge begins in London.

• Copley Medal: Not awarded^[7]

• January 19 – Alfred Clebsch (died 1872), German mathematician.
• February 26 – Georges Pouchet (died 1894), French comparative anatomist.
• March 14 – Lucy Hobbs Taylor (died 1910), American dentist.
• March 23 – Karl Friedrich Otto Westphal (died 1890), German psychiatrist.
• March 25 – Fleeming Jenkin (died 1885), English electrical engineer.
• May 5 – Ferdinand von Richthofen (died 1905), German geographer.
• June 29 – Peter Waage (died 1900), Norwegian chemist.
• October 9 – Eugen Langen (died 1895), German mechanical engineer.
• October 17 – Paul Bert (died 1886), French physiologist.
• October 21 – Alfred Nobel (died 1896), Swedish inventor.
• November 27 - Émile Vallin (died 1924), French military physician.^[8]
• December 2 – Friedrich Daniel von Recklinghausen (died 1910), German pathologist.

• January 10 – Adrien-Marie Legendre (born 1752), mathematician.
• February 6
  • Fausto Elhuyar (born 1755), chemist
  • Pierre André Latreille (born 1762), zoologist.
• February 14 – Gottlieb Kirchhoff (born 1764), chemist.
• April 22 – Richard Trevithick (born 1771), engineer and inventor.
• May 15 – Bewick Bridge (born 1767), mathematician.
• July 5 – Nicéphore Niépce (born 1765), inventor.
• October 31 – Johann Friedrich Meckel (born 1781), anatomist.