Rising trend is known as 'showrooming'.
New data from Aprimo and Forrester Research claims one in five American shoppers are visiting stores to get hands-on with products, but then going on to use their mobiles to check for a cheaper price online.
The trend is called 'showrooming' and 33 per cent of those making use of the technique admit to buying elsewhere, which is expected to rise as 96 per cent of respondents say they'll use their smartphone for research in the future.
Sucharita Mulpuru, VP and principal analyst for Forrester Research, said: "This research confirms what many in the retail industry have suspected: Showrooming is here to stay."
Meanwhile, a third of the people that haven't used their phones for in-store research admit they haven't done so because the idea hadn't occurred to them until now.
Electronic items are the most popular ones to get price checked in-store at 39 per cent, followed by groceries with 37 per cent, and clothing and footwear at 33 per cent.
Unsurprising, retailers with lower prices stand to benefit from showrooming, with more than half of consumers discovering lower prices online than in the store and just eight percent claiming to have seen higher prices.
Marc Schroeder, VP of industry solutions at Aprimo, said: "The opportunity here is to leverage technology and common sense and shift to a customer-centric value proposition through better service, smarter timing and relevant offers.
"Retailers need new ways to build loyalty and brand value; physical-store retailers will not win in the long run by focusing only on price matching."