Tesco says it is the first retailer in Ireland to remove plastic wrapping on some multi-packs in its 151 stores.
The company says 1.5 million multi-packs of its own brand tinned beans, tuna, soup and tomatoes will be sold without plastic.
Plastic will still be used though on drink multi-packs and on vegetables although it has pledged to cut plastic across its business.
But Mindy O'Brien, from conservation group Voice Ireland, says it is only a small step in a big industry.
"I was doing the calculations that they are reducing their plastic packaging waste by 10 tonnes. In Ireland we are producing 280,000 tonnes of plastic packaging a year," she said.
"So that equates to about 0.003% of our plastic packaging"
Ms O'Brien says change in the supermarket sector is not happening fast enough.
"It is very slow, I'm seeing in my own shop they are offering much more loose vegetables but then often times the loose vegetables are more expensive than those that are bagged in plastic," said Ms O'Brien.
"I am not allowed to bring my own container when buying meat or fish.
"They won't allow me to do that to allow me to avoid the use of packaging.
"We need to be allowed to use our own containers. This is being done in France, in Italy and around Europe."