Underlying earnings fell 4% to $4.75 billion.

Macquarie had been expecting EBITDA of $9.5 billion and underlying NPAT of $4.5 billion, but noted its forecasts were slightly ahead of consensus.

Net earnings were down 20% to $3.3 billion, which included $1 billion of impairments of four aluminium smelters and the Diavik diamond mine in Canada, as well as exchange rate movements.

Rio CEO J-S Jacques said the company had been agile and adapted due to COVID-19.

"In extraordinary times, we are showing our strength and resillience," he told reporters this afternoon.

Iron ore accounted for $7.7 billion of underlying EBITDA, up 2%, and $4.56 billion of underlying earnings, up 1%.

Underlying earnings and EBITDA fell by double-digit percentages for all other divisions.

Free cashflow dropped 28% to $2.8 billion, reflecting a 12% fall in operating cashflow to $5.6 billion due to lower commodity prices and a 13% rise in capital expenditure to $2.7 billion.

Rio declared an interim dividend of $1.55 per share, or $2.5 billion, representing a payout ratio of 53% of underlying earnings.

It was below Macquarie's forecast of $1.70 per share, while the bank had also highlighted the potential for a $1 per share special dividend due to the high iron ore price and low gearing.

Gearing increased from 7% at December 31 to 10% at June 30, with gross debt of $13.9 billion and net debt of $4.8 billion.

"Our world-class portfolio of high-quality assets and our strong balance sheet consistently serve us well in all market conditions and particularly in turbulent times," Jacques said.

"This, together with our disciplined capital allocation, underpins our ability to sustain production, increase our investment in the business, pay taxes and royalties to governments and continue delivering superior returns to shareholders."

Shares in Rio closed 0.7% lower at A$103.40 just prior to the release of the results.