1852 (MDCCCLII) was a leap year starting on Thursday (dominical letter DC) of the Gregorian calendar and a leap year starting on Tuesday (dominical letter FE) of the Julian calendar, the 1852nd year of the Common Era (CE) and Anno Domini (AD) designations, the 852nd year of the 2nd millennium, the 52nd year of the 19th century, and the third year of the 1850s decade. As of the start of 1852, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localised use until 1918.
- January 14 – President Louis-Napoléon Bonaparte proclaimed a new constitution for the French Second Republic.
- January 15 – Nine men representing various Jewish charitable organizations came together to form what became the Mount Sinai Hospital in New York City.
- January 17 – The United Kingdom recognised the independence of the Transvaal.
- February 3 – Battle of Caseros or Battle of Monte Caseros, Argentina: The Argentine provinces of Entre Rios and Corrientes allied with Brazil and members of Colorado Party of Uruguay, defeated Buenos Aires troops under Juan Manuel de Rosas.
- February 11 – The first British public toilet for women was opened in Bedford Street, London.
- February 15 – The Great Ormond Street Hospital for Sick Children, London, admitted its first patient.
- February 16 – The Studebaker Brothers Wagon Company, precursor of the automobile manufacturer, was established.
- February 25 – HMS Birkenhead sank near Cape Town, British Cape Colony. Only 193 of the 643 on board survived after troops stood firm on the deck so as not to flood the lifeboats containing women and children.
- March 1 – Archibald Montgomerie, thirteenth Earl of Eglinton was appointed Lord Lieutenant of Ireland.
- March 2 – The first American experimental steam fire engine was tested.
- March 4 – Phi Mu sorority was founded in Macon Georgia
- March 20 – Uncle Tom's Cabin by Harriet Beecher Stowe was published in book form in Boston.
- April 1 – The Second Anglo-Burmese War began.
- April 18 – Taiping Rebellion: Taiping forces began the siege of Guilin.
- May 19 – Taiping Rebellion: The siege of Guilin was lifted.
- June 12 – Taiping Rebellion: Taiping forces entered Hunan.
- July 1 – United States statesman Henry Clay was the first to receive the honour of lying in state in the United States Capitol rotunda.
- July 5 – Frederick Douglass delivered his famous speech "What to the Slave is the Fourth of July?" in Rochester, New York.
- July 28 – Henry Clay steamboat disaster in Riverdale, Bronx, with several deaths including Stephen Allen.
- August 3 – The first Boat Race between Yale and Harvard, the first American intercollegiate athletic event, was held.
- September 24 – French engineer Henri Giffard made the first airship trip from Paris to Trappes.
- October 7 — After learning that U.S. President Fillmore has sent Commodore Matthew C. Perry, to open trade with Japan, Nicholas I of Russia sent Rear Admiral Yevfimy Putyatin to lead the Pallada on a similar mission. Putyatin arrived on August 21, 1853, one month after Perry.
- October 16 — After nearly five years imprisonment in France, former Algerian Emir Abdelkader El Djezairi was released by orders of then-president Louis-Napoléon Bonaparte.
- October 23 — The conjecture of the four colour theorem was first proposed, as student Francis Guthrie of University College London presented the question of proving, mathematically, that no more than four colours are needed to give separate colours to bordering shapes on a map. The theorem wasn't proven for almost 123 years, until 1976.
- October 31 — General Joaquin Solares of Guatemala led an invasion of neighbouring Honduras, beginning a war that lasted until February 13, 1856.
- November 2 – U.S. presidential election, 1852: Democrat Franklin Pierce of New Hampshire defeated Whig Winfield Scott of Virginia.
- November 4 – Camillo Benso, Count of Cavour becomes the Piedmontese prime minister.
- November 11 – The new Palace of Westminster was opened in London.
- November 21–22 – The New French Empire was confirmed by plebiscite: 7,824,000 for, 253,000 against.
- November 23 – The first roadside pillar boxes in the British Isles were brought into public use in Saint Helier on Jersey in the Channel Islands at the suggestion of English novelist Anthony Trollope, at this time an official of the British General Post Office.
- December – The Western Railroad was chartered to build a railroad from Fayetteville, North Carolina to the coal fields of Egypt, North Carolina.
- December 2 – Napoleon III became Emperor of the French.
- December 4 – The French captured Laghouat.
- December 23 – Taiping Rebellion: The Taiping army took Hanyang and begins the siege of Wuchang.
- December 29 – Taiping Rebellion: The Taiping army took Hankou.
- The semaphore line in France was superseded by the telegraph.
- Justin Perkins, an American Presbyterian missionary, produced the first translation of the Bible in Assyrian Neo-Aramaic, which was published with the parallel text of the Syriac Peshitta by the American Bible Society.
- The Devil's Island penal colony was opened.
- In Hawaii sugar planters brought over the first Chinese labourers on 3 or 5 year contracts, giving them 3 dollars per month plus room and board for working a 12-hour day, 6 days a week.
- Loyola College was chartered in Baltimore, Maryland.
- Germans were encouraged to immigrate to Chile
- Gef's supposed birth
- Antioch College was founded. Its first president was Horace Mann.
- Mills College was founded.
- Leo Tolstoy's first novel, Childhood, was published in book form.
- January 8 – James Milton Carroll, Baptist pastor, leader, historian, and author (d. 1931)
- January 11 – Constantin Fehrenbach, Chancellor of Germany (d. 1926)
- January 18 – Augustin Boué de Lapeyrère, French admiral (d. 1924)
- January 20 – José Guadalupe Posada,Mexican political printmaker and engraver (d.1913)
- February 16 – Charles Taze Russell (Pastor Russell), prominent Protestant reformer and evangelist (d. 1916)
- February 26 – John Harvey Kellogg, American doctor (d. 1943)
- February 26 – Felix von Winiwarter, Austrian physician (d.1931)
- February 29 – Frederic, one of the protagonists in Gilbert and Sullivan's operetta The Pirates of Penzance (date of death unknown)
- March 1 – Théophile Delcassé, French statesman (d. 1923)
- April 1 – Edwin Austin Abbey, American painter (d. 1911)
- April 13 – F. W. Woolworth, American merchant and businessman (d. 1919)
- April 22 – William IV, Grand Duke of Luxembourg (d. 1912)
- May 1 – Santiago Ramón y Cajal, Spanish histologist, recipient of the Nobel Prize in Physiology or Medicine (d. 1934)
- May 4 – Alice Pleasance Liddell, inspiration for the children's classic Alice's Adventures in Wonderland by Lewis Carroll (d. 1934)
- May 11 – Charles W. Fairbanks, 26th Vice President of the United States (d. 1918)
- May 14 – Émile Fayolle, French general (d. 1928)
- May 15 – Louisa Adams, First Lady of the United States (b. 1775)
- May 31 – Julius Richard Petri, German bacteriologist (d. 1921)
- June 13 – Anna Whitlock, Swedish women's right activist (d. 1930)
- June 25 – Friedrich Loeffler, German bacteriologist (d. 1915)
- June 25 – Antoni Gaudí, Spanish modernist architect (d. 1926)
- June 30 – Karl Petrovich Jessen, Russian admiral (d. 1918)
- July 12 – Hipólito Yrigoyen, President of Argentina (d. 1933)
- July 31 – Charles Lanrezac, French general (d. 1925)
- August 4 – Catharine van Tussenbroek, Dutch physician (d. 1925)
- August 23 – Clímaco Calderón, President of Colombia (d. 1913)
- August 30 – Jacobus Henricus van 't Hoff, Dutch chemist, Nobel Prize laureate (d. 1911)
- September 6 – Schalk Willem Burger, Boer military leader, lawyer, politician, and statesman, acting President of the South African Republic (1900-1902) (d. 1918)
- September 8 – Gojong, 26th king of the Korean Joseon dynasty and the first emperor of Korea (d. 1919)
- September 10 – Hans Niels Andersen, Danish businessman, founder of the East Asiatic Company (d. 1937)
- September 12 – Herbert Henry Asquith, Prime Minister of the United Kingdom (d. 1928)
- September 15 – Edward Bouchet, American physicist (d. 1918)
- September 28
- September 30 – Charles Villiers Stanford, Irish composer, resident in England (d. 1924)
- October 2 – William Ramsay, Scottish chemist, Nobel Prize laureate (d. 1916)
- October 9 – Hermann Emil Fischer, German chemist, Nobel Prize laureate (d. 1919)
- October 17 – George Egerton, British admiral (d. 1940)
- October 25 – Byron Andrews, journalist, statesman, author, businessman.
- November 1 – Eugene W. Chafin, American politician (d. 1920)
- November 3 – Prince Mutsuhito of Japan, the future Emperor Meiji (d. 1912)
- November 11 – Franz Conrad von Hötzendorf, Austro-Hungarian field marshal (d. 1925)
- November 22 – Paul-Henri-Benjamin d'Estournelles de Constant, French diplomat, recipient of the Nobel Peace Prize (d. 1924)
- November 26 – Yamamoto Gonnohyōe, the sixteenth and twenty-second Prime Minister of Japan, an admiral in the Imperial Japanese Navy
- December 15
- December 19 – Albert Abraham Michelson, German-born physicist, Nobel Prize laureate (d. 1931)
- December 21 – George Callaghan, British admiral (d. 1920)
- January 1 – John George Children, British chemist, mineralogist and zoologist (b. 1777)
- January 6 – Louis Braille, French teacher of the blind and inventor of braille (b. 1809)
- May 3 – Sara Coleridge, English author and translator (b. 1802)
- March 4 – Nikolai Gogol, Russian writer (b. 1809)
- April 17 – Étienne Maurice Gérard, Marshal of France and Prime Minister of France (b. 1773)
- June 7 – José Joaquín Estudillo, second alcalde of Yerba Buena (b. 1800)
- June 21 – Friedrich Fröbel, German pedagogue (b. 1782)
- June 29 – Henry Clay, American statesman (b. 1777)
- July 20 – José Antonio Estudillo, early California settler (b. 1805)
- July 22 – Auguste de Marmont, French marshal (b. 1774)
- August – Táhirih, Iranian Bahai theologian, poet and feminist (b. 1814)
- August 14 – Margaret Taylor, First Lady of the United States (b. 1788)
- September 4 – William MacGillivray, Scottish naturalist and ornithologist (b. 1796)
- September 8 – Anna Maria Walker, Scottish botanist (d. 1778)
- September 14
- September 20 – Philander Chase, American founder of Kenyon College (b. 1775)
- October 7 – Sir Edward Troubridge, second Baronet, British admiral (b. ca. 1787)
- October 13 – John Lloyd Stephens, American traveler, diplomat and Mayanist archaeologist (b. 1805)
- October 15 – Friedrich Ludwig Jahn, German gymnastics educator (b. 1778)
- October 24 – Daniel Webster, American statesman (b. 1782)
- October 25 – John C. Clark, American politician (b. 1793)
- October 26 – Vincenzo Gioberti, Italian philosopher (b. 1801)
- November 2 – Pyotr Kotlyarevsky, Russian military hero (b. 1782)
- November 17 – Adam Karl August von Eschenmayer, German philosopher (b. 1768)
- November 18 – John Andrew Shulze, American politician (b. 1775)
- November 27 – Augusta Ada King (née Byron), Countess of Lovelace, early English computer pioneer (b. 1815)
- November 29 – Nicolae Bălcescu, Wallachian revolutionary (b. 1819)
- November 30 – Junius Brutus Booth, English-born actor (b. 1796)
- December 16 – Andries Hendrik Potgieter, Voortrekker leader (b. 1792)
- date unknown – Joanna Żubr, Polish soldier (b. 1770)