Official figures show spending using debit, credit and charge cards rose a seasonally adjusted 1.2 percent in May, following a fall of 0.7 percent in April.
People also spent more on fuel in May - excluding cars and fuel, core retail spending rose a modest 0.4 percent.
Westpac senior economist Felix Delbruck said the pick-up was disappointing.
"Some of that momentum [from the early part of the year] has come off... partly due to the windfall consumers were getting from cheaper petrol, rather than an underlying pick up in the economy."
On an annual basis, spending jumped 3.2 percent when compared to May last year.