Group sales at the UK's third-biggest co-op rose 3.1% to £387m in the 26 weeks to 23 July, with profits of £15.8m.
CEO Ben Reid said the profit figure would have been a record for the society if the £1.3m it spent on setting up its new Co-operative Energy business had not been included.
"It is a testimony to the strength of our business model that we can launch a national business such as Co-operative Energy, absorb the initial cost, but still produce an outstanding trading result," he said.
"By continuing to concentrate on getting the fundamentals of our business right we can emerge from this recession stronger."
Meanwhile, Essex-based co-op society Chelmsford Star has reported record half-year results following an expansion of its food business.