The Co-op's new loyalty programme, which encourages members to buy own-brand products and support local charities, will be secured using ACI's UP Merchant Payments solution.
ACI will run the Co-op's cloud-based wallet service, which was launched last year. Over five million members will also receive new membership cards.
Following a trial, the new scheme reported a significant jump in transactions, turnover and frequency of visits, while sales in own-brand products also increased.
ACI is also rolling out its card payment service to all Co-op food and fuel stores in the UK. The Point-2-Point Encryption (P2PE) protects cardholder data by converting confidential credit and debit card data into indecipherable codes when the card is read by the payment terminal.