Clothing retailer Primark, which owns Penneys, made operating profits of £59m in the six months to March 5, an 18% increase on the same period a year earlier, according to its parent company Associated British Foods.
Sales rose by 12% to £448m, with an increase of 6% when the effect of new stores was stripped out.
Primark has more than 120 stores in Britain and Ireland. Penneys will open a larger store in Mullingar by the end of the year and also plans a new store in Dundalk before Christmas.