The year 1709 in science and technology involved some significant events.

• January – Great Frost in Western Europe.^[1][2]

• Francis Hauksbee publishes Physico-Mechanical Experiments on Various Subjects, summarizing the results of his many experiments with electricity and other topics.

• January 10 – Industrial Revolution: Abraham Darby I successfully produces cast iron using coke fuel at his Coalbrookdale blast furnace in Shropshire, England.^[3][4][5]
• February 5 – Dramatist John Dennis devises the thundersheet as a new method of producing theatrical thunder for his tragedy Appius and Virginia at the Theatre Royal, Drury Lane, London.^[6]
• March 28 – Johann Friedrich Böttger reports the first production of hard-paste porcelain in Europe, at Dresden.
• July 13 – Johann Maria Farina founds the first Eau de Cologne and perfume factory in Cologne, Germany.
• August 8 – Hot air balloon of Bartholome de Gusmão flies in Portugal.
• A collapsible umbrella is introduced in Paris.^[7]

• April 9 – Sir Godfrey Copley, 2nd Baronet dies and in his will provides funding to the Royal Society for the annual Copley Medal honoring achievement in science (first awarded in 1731).

• February 24 – Jacques de Vaucanson, French engineer and inventor (died 1782)
• March 3 – Andreas Sigismund Marggraf, German chemist (died 1782)
• March 10 – Georg Steller, German naturalist (died 1746)
• April 17 – Giovanni Domenico Maraldi, French-Italian astronomer (died 1788)
• July 11 – Johan Gottschalk Wallerius, Swedish chemist and mineralogist (died 1785)
• August 8 – Johann Georg Gmelin, German botanist (died 1755)
• November 23 – Julien Offray de La Mettrie, French physician and philosopher (died 1751)

• early – Eleanor Glanville, English entomologist (born c. 1654)
• June 29 – Antoine Thomas, Belgian Jesuit astronomer in China (born 1644)
• June 30 – Edward Lhuyd, Welsh naturalist (born 1660)
• October 17 – François Mauriceau, French obstetrician (born 1637)