James Beaumont Neilson (22 June 1792 – 18 January 1865) was a Scottish inventor whose hot-blast process greatly increased the efficiency of smelting iron.

Experiments were continued at Clyde Iron Works, leading to his forming a partnership with Charles Macintosh and others to exploit it.

[1] Experimentation showed that a temperature of 600°F reduced fuel consumption to a third of that with cold blast, and enabled raw coal to be used instead of coke, with a further cost saving.

After that, Neilson and his partners licensed it widely at one shilling per ton iron made, a level low enough to discourage evasion.

Neilson v Baird was heard in the Court of Session in 1843, in a trial lasting 10 days and costing £40,000.