Matthew Boulton, the son of a silver-stamper, was born in Birmingham on 14th September 1728. His father also became involved in making toys. At the age of twenty-one he became a partner in his father's business. Jenny Uglow, the author of The Lunar Men (2002), has argued: "Boulton was neat and dark and dapper, with curly brown hair, keen eyes and a broad grin. Frank and humorous, always with an eye to the main chance, he was a man on the make."
Boulton married Mary Robinson, the daughter of wealthy merchant. On the death of her parents she inherited £14,000. Mary died in 1760 and there were no surviving children. His father also died around the same time, leaving the business to his son. Boulton later married Anne, Mary's younger sister. This was forbidden by ecclesiastical law but Boulton still went ahead with the wedding. According to his biographer, Jennifer Tann: "Boulton's marriage, and with it the addition to his fortune, was the cause of a number of letters of congratulations from his friends. Later in his life, alluding to his fortune, he remarked that he had had the option of living the life of a gentleman but chose, rather, to become an industrialist."
Matthew Boulton became a member of the Lunar Society of Birmingham. The group took this name because they used to meet to dine and converse on the night of the full moon. Other members included James Watt, Josiah Wedgwood, Joseph Priestley, Thomas Day, William Small, John Whitehurst, William Withering, Richard Lovell Edgeworth and Erasmus Darwin. The historian, Jenny Uglow, has argued: "The members of the Lunar Society were brilliant representatives of the informal scientific web that cut across class, blending the inherited skills of craftsmen with the theoretical advances of scholars, a key factor in British manufacturing's leap ahead of the rest of Europe. Most had been entranced by mechanics in childhood in the 1730s and 1740s, when itinerant lecturers toured the country displaying electrical and mechanical marvels."
In 1763 James Watt was sent a Newcomen steam engine to repair. While putting it back into working order, Watt discovered how he could make the engine more efficient. Watt worked on the idea for several months and eventually produced a steam engine that cooled the used steam in a condenser separate from the main cylinder. James Watt was not a wealthy man so he decided to seek a partner with money. John Roebuck, the owner of a Scottish ironworks, agreed to provide financial backing for Watt's project.
When Roebuck went bankrupt in 1773, he owed Boulton over £1,200. Boulton knew about Watt's research and wrote to him making an offer for Roebuck's share in the steam-engine. Roebuck refused but on 17th May, he changed his mind and accepted Boulton's terms. Watt was also owed money by Roebuck, but as he had done a deal with his friend, he wrote a formal discharge "because I think the thousand pounds he (Boulton) he has paid more than the value of the property of the two thirds of the inventions."
For the next eleven years Boulton's factory producing and selling Watt's steam-engines. These machines were mainly sold to colliery owners who used them to pump water from their mines. Watt's machine was very popular because it was four times more powerful than those that had been based on the Thomas Newcomen design. The first major market for Boulton and Watt engines was in Cornwall.
Boulton continued to produce other goods. In September 1778, Boulton commented "how far it may be prudent in me to stick to Engines or Buttons for I can consider Buttons as a sheet anchor". Jennifer Tann has argued: "It would be incorrect to stereotype Boulton as the entrepreneur and Watt as the inventor, for Boulton made many suggestions for improvements to the engine and Watt also had a good head for business. But there is no doubt that Boulton's flair for marketing was significant for the early success of the business."
It was Boulton who perceived the potential afforded by the growth of the cotton-spinning industry and urged James Watt to develop a rotative engine. By 1781 the new rotary-motion steam engine was ready. Whereas his earlier machine, with its up-and-down pumping action, was ideal for draining mines, this new steam engine could be used to drive many different types of machinery. Richard Arkwright was quick to see the importance of this new invention, and in 1783 he began using steam-engines in his textile factories. Others followed his lead and after fifteen years there were over 500 of Boulton & Watt's machines in Britain's mines and factories.
Eric Hobsbawm, the author of The Age of Revolution (1962) has argued: "Fortunately few intellectual refinements were necessary to make the Industrial Revolution. Its technical inventions were exceedingly modest, and in no way beyond the scope of intelligent artisans experimenting in their workshops, or of the constructive capacities of carpenters, millwrights, and locksmiths: the flying shuttle, the spinning jenny, the mule. Even its scientifically most sophisticated machine, James Watt's rotary steam-engine (1784), required no more physics than had been available for the best part of a century."
Arthur Young pointed out in his book, From Birmingham to Suffolk (1791): "What trains of thought, what a spirit of exertion, what a mass and power of effort have sprung in every path of life, from the works of such men as Brindley, Watt, Priestley, Harrison, Arkwright.... In what path of life can a man be found that will not animate his pursuit from seeing the steam-engine of Watt?"
In 1786 Boulton applied steam power to coining machines. So successful was the process that as well as his supplying the home market, he produced coins for foreign governments as well. As Jennifer Tann pointed out: "A mint to supply copper coinage to the government was established at Soho Manufactory. Towards the end of the eighteenth century Boulton undertook the supply of complete mints for overseas customers, the first one being the imperial mint in St Petersburg. Other orders followed and one of his last commissions before his death was the new Royal Mint in London. It was particularly for his mint interests that he sought out expert engravers and die-sinkers from continental Europe to enhance the level of skill at Soho Manufactory. By means of his mint machinery and the flow-production system in which it was deployed he achieved greater accuracy in the finished product."
Boulton was a supporter of the campaign against slavery. In 1789, along with Joseph Priestley, he joined the deputation to welcome Olaudah Equiano, who came to speak in Birmingham about his experiences as a slave.