Darwin has shown unexpected growth in RP Data's Home Value Index for July, rising 3.2%.
Meanwhile, Adelaide fell by 2.3%, making it the weakest-performing capital city.
Sydney remains the country's most expensive city to buy a property, while Hobart is the cheapest.
RP Data's results are increasingly anticipated in the industry, after last month's results - which showed a sudden spike in value in Hobart - caused serious debate in the industry.
At the time, RP Data's competitor, SQM, questioned its methodology and disputed claims of a growth in capital cities, particularly Melbourne.
Tim Lawless, RP Data's research director, said July's results were "not as broad-based as the June results."
“The month-on-month increase [is] primarily being associated with the Sydney and Melbourne markets where dwelling values rose 1.2 per cent and 1.4 per cent respectively."
"The July result, when viewed together with the positive June result, suggests housing markets may be starting to respond to lower mortgage rates, which according to the RBA’s latest Board meeting minutes are around 50 basis points below their 15-year average,” he said.
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