Sir William Robert Grove, FRS FRSE (11 July 1811 – 1 August 1896) was a Welsh judge and physical scientist.

Born in Swansea, Wales, Grove was the only child of John, a magistrate and deputy lieutenant of Glamorgan, and his wife, Anne (née Bevan).

[2] His early education was in the hands of private tutors, before he attended Brasenose College, Oxford to study classics, though his scientific interests may have been cultivated by mathematician Baden Powell.

In the same year, Grove joined the Royal Institution and was a founder of the Swansea Literary and Philosophical Society, an organisation with which he maintained close links.

[6] Later that year, he gave another account of his development at the British Association for the Advancement of Science meeting in Birmingham, where it aroused the interest of Michael Faraday.

[3] In 1842, Grove developed the first fuel cell (which he called the gas voltaic battery), which produced electrical energy by combining hydrogen and oxygen, and described it using his correlation theory.

[3] In developing the cell and showing that steam could be disassociated into oxygen and hydrogen, and the process reversed, he was the first person to demonstrate the thermal dissociation of molecules into their constituent atoms.

[13] Inspired by his legal practice, he presciently observed:[13] It would be vain to attempt specifically to predict what may be the effect of Photography on future generations.

A Process by which the most transient actions are rendered permanent, by which facts write their own annals in a language that can never be obsolete, forming documents which prove themselves, – must interweave itself not only with science but with history and legislature.

In 1852, he discovered striae, dark bands that occur in electrical breakdown, and investigated their character, presenting his work in an 1858 Bakerian lecture.

Thomson's public champion, Peter Guthrie Tait was initially a supporter of Grove's ideas but later dismissed them with some coolness.

[18] Though Groves's ideas were forerunners of the theory of the conservation of energy, they were qualitative, unlike the quantitative investigations of Joule or Julius Robert von Mayer.

[3] From 1846 Grove started to reduce his scientific work in favour of his professional practice at the bar, his young family providing the financial motivation; and in 1853 became a QC.

[3] The bar provided him with the opportunity to combine his legal and scientific knowledge, in particular in patent law[7] and in the unsuccessful defence of poisoner William Palmer in 1856.

[3] He was to have presided at the Cornwall and Devon winter assizes of 1884, which would have entailed him trying the notorious survival cannibalism case of R v. Dudley and Stephens.