James Neilson was born in Shettleston and after leaving school at the age of fourteen became a gig boy at the Govan colliery, responsible for minding a winding engine. He was apprenticed as an engineer at the age of sixteen and went on to work at a colliery in Irvine. In 1817 he was appointed manager of the newly established Glasgow Gas Company, a post he was to hold for forty years.
During the 1820s he was invited to correct a fault which had developed in a blast furnace at the Muirkirk Iron Company. On inspection it occurred to him that he could increase the force of the blast by passing hot rather than cold air through the red-hot vessel. He then set about conducting experiments in the smithy at the gas works where he proved his theory to be correct. After further trials at a foundry in Malta Street, he patented his hot-blast process in 1828.
The process was first introduced commercially at the Clyde Iron Works of Colin Dunlop, who had a financial stake in the patent. There were initial teething troubles which were not finally resolved until 1834. Nevertheless the process quickly proved its worth through significant savings in fuel consumption and was rapidly adopted throughout the west of Scotland iron industry. Frequently challenged as the inventor of the hot-blast, James Beaumont Neilson successfully defended his claim in a number of actions, notably in 1843 against the Bairds of Gartsherrie.
He became a rich man and a keen advocate of technical education.