Tesco's IT director, Ian O'Reilly, has handed in his notice after nine years in charge of the department to join an e-commerce company.
O'Reilly's departure comes only months after Tesco unveiled ambitious plans to develop its home shopping arm, Tesco.com.
O'Reilly, who leaves in September, is just the latest in a growing number of senior IT staff leaving established firms for e-commerce businesses. Earlier this year, Mike Winch, IT director of Safeway, left to join an Internet start-up after a 17-year spell at the company.
Philip Clarke, Tesco's IT and logistics director will take over as IT director until the company finds a replacement. Tesco expects to make an announcement by the autumn, and is looking at both internal and external candidates.
Strong contenders for the post are believed to include John Lister, former IT director of Asda, who recently joined Tesco as European IT director, and Doug Routledge, IT director for South East Asia.
"This is no criticism of Tesco. We have seen the best technical people being lured to dotcoms because of the excitement in the sector, and the prospect of share options. People sometimes need a new challenge," said Mike Godliman, director at retail consultancy Verdict.
Under O'Reilly, Tesco has become one of the leading users of IT in the UK retail industry. Tesco's checkout technology, Club Card and home shopping sites, have made a major impact, said Godliman.
Tesco announced plans to invest £35m in Tesco.com, earlier this year, to develop the retailer's home shopping business. It will operate as a separate business unit and will report its own financial results.
"Ian leaves us with only our very best wishes and we thank him for the contribution he has made to the success of our systems portfolio," said Tesco.