Tesco is running a pilot using sat-nav technology to help customers navigate around stores and locate stock.
The supermarket giant told Computing last year that it was experimenting with the technology using iPads and iPhones, but the new system, installed at the Tesco Extra in Gallows Corner, Romford, north-east London, is currently only available to Android phone owners.
Nick Lansley, head of research and development (R&D), explained that the service is only available to Android phone owners who contact Tesco for a link to download the app.
The app is not yet available on public app stores because the supermarket does not want the app in its current state going into those stores.
"Only Android easily offers the ability to install apps from unknown sources," he said.
He added that the supermarket chain will not be rolling out the service to all its retail stores as yet because it has to determine how useful the technology is going to be.
"The system involves a lot of infrastructure installation in the stores so we need to get all kinds of people involved in thinking about the customer experience. It would be awful if we did all this work but few customers really used it."
Tesco had already been trialling scan-as-you-shop technology in the Romford store using handheld scanners developed internally, and Lansley is looking to recruit a large control group of customers to try it out on their Android smartphones.
He has posted instructions on how customers can get involved on the Tech for Tesco blog.