Henry Cavendish was born on 10 October 1731 in Nice, where his family was living at the time. His mother was Lady Anne de Grey, fourth daughter of Henry Grey, 1st Duke of Kent, and his father was Lord Charles Cavendish, the third son of William Cavendish, 2nd Duke of Devonshire. The family traced its lineage across eight centuries to Norman times, and was closely connected to many aristocratic families of Great Britain. Henrys mother died in 1733, three months after the birth of her second son, Frederick, and shortly before Henrys second birthday, leaving Lord Charles Cavendish to bring up his two sons. Henry Cavendish was styled as "The Honourable Henry Cavendish".
From the age of 11 Henry attended Newcomes School, a private school near London. At the age of 18 (on 24 November 1748) he entered the University of Cambridge in St Peters College, now known as Peterhouse, but left three years later on 23 February 1751 without taking a degree (at the time, a common practice). He then lived with his father in London, where he soon had his own laboratory.
Lord Charles Cavendish spent his life firstly in politics and then increasingly in science, especially in the Royal Society of London. In 1758, he took Henry to meetings of the Royal Society and also to dinners of the Royal Society Club. In 1760, Henry Cavendish was elected to both these groups, and he was assiduous in his attendance after that. He took virtually no part in politics, but followed his father into science, through his researches and his participation in scientific organisations. He was active in the Council of the Royal Society of London (to which he was elected in 1765).
His interest and expertise in the use of scientific instruments led him to head a committee to review the Royal Societys meteorological instruments and to help assess the instruments of the Royal Greenwich Observatory. His first paper, Factitious Airs, appeared in 1766. Other committees on which he served included the committee of papers, which chose the papers for publication in the Philosophical Transactions of the Royal Society, and the committees for the transit of Venus (1769), for the gravitational attraction of mountains (1774), and for the scientific instructions for Constantine Phippss expedition (1773) in search of the North Pole and the Northwest Passage. In 1773, Henry joined his father as an elected trustee of the British Museum, to which he devoted a good deal of time and effort. Soon after the Royal Institution of Great Britain was established, Cavendish became a manager (1800) and took an active interest, especially in the laboratory, where he observed and helped in Humphry Davy's chemical experiments.