COOPERS BREWERY will become the biggest supplier of home brew beer kits and products in the United States, as well as globally, after agreeing to buy Mr Beer for an undisclosed sum.

It marks the Adelaide brewer's first international acquisition in 30 years.

No longer the hobby of pensioners brewing beer in old bathtubs in their sheds, the home brew industry in North America has blossomed into a $100 million a year market with growth rates of more than 20 per cent a year.

Coopers, the family owned company that this year celebrates its 150th birthday, will now sit atop the market in America after buying the Arizona-based Mr Beer, which distributes home brew starter kits, concentrates and accessories to more than 14,000 stores and online.

It has purchased 80 per cent of the business, with the remaining 20 per cent held by the home brew company's former owner and IT entrepreneur Mike Bernstein.

The acquisition will add to Coopers' Australian home brew business, which controls more than 80 per cent of the local market.

Coopers would not release the revenue and profitability of Mr Beer but it is believed the business, established in 1993, has annual turnover of roughly $10 million. Coopers, which is now Australia's biggest locally owned brewery after SABMiller's $12 billion takeover of Foster's last year, has annual revenues of about $200 million of which $30 million comes from its home brewing business.

Coopers' marketing manager, brewing products, Scott Harris, said Mr Beer would be profitable immediately and would open new opportunities for Coopers in the US market, including showcasing its home brew products in non-traditional retail outlets.

"The potential home brew market in the US is huge,'' Mr Harris said.

''In 2011, Mr Beer sold more than 200,000 home brew starter kits and there are no signs of that demand waning. In the past 10 years demand has been increasing by about 10 per cent a year."

The American Homebrewers Association says there are more than 1 million home brewers in the US and 1000 clubs.

Alabama and Mississippi remain the only states in the US where home brewing is illegal.

Mr Harris said that the Mr Beer brand would be retained, along with its existing two gallon (8 litre) micro brew kits.

But he said customers would notice changes aimed at improving the quality of the beer.

"We will replace the current malt extracts with a superior quality all-malt concentrate produced at Coopers with a yeast specifically designed for their size kit.''