BHP Billiton chief executive Marius Kloppers is stepping down after nearly six years as head of the global mining giant.
Mr Kloppers will be replaced on May 10 by Andrew Mackenzie, the 56-year-old Scottish head of the BHP's metals business.
The news came as BHP posted 58 per cent fall in first half profit due to lower commodity prices, a weak US dollar and the sale of some its businesses.
"Deciding the right time to retire was never going to be easy," Mr Kloppers said in a statement on Wednesday.
"However, after almost 20 years with BHP Billiton, 12 as a senior executive and nearly six as CEO, I believe now is the right time to pass (on) the leadership baton."
BHP's leadership change comes just over a month since Rio Tinto's chief executive Tom Albanese was replaced by its head of iron ore operations Sam Walsh.
Mr Mackenzie will move to Melbourne in the coming months before taking up the top job.
BHP's net profit in the six months to December 31 of $US4.24 billion ($A4.14 billion) was down from $US9.94 billion ($A9.70 billion) in the previous corresponding period.
The result included $US1.4 billion ($A1.37 billion) in one-off costs from asset sales.
Profit excluding one-off items was $US5.7 billion ($A5.56 billion) in the six months to December, down 43 per cent from $US9.94 billion ($A9.70 billion) for the December 2011 half but in line with analyst expectations.
The fall in underlying profit was caused by falls in iron ore and other commodity prices in 2012.
Underlying earnings before interest and tax (EBIT) of $US9.8 billion ($A9.57 billion) were down 38 per cent from $US15.7 billion ($A15.32 billion), but slightly higher than analyst expectations.
BHP said that, notwithstanding short-term volatility, a modest improvement in the global economy was anticipated over the next 12 months.
The company said it was optimistic about the Chinese government's policies supporting stable growth, while the US was benefiting from relatively low energy costs.
Eurozone markets had stabilised following the European Central Bank's commitment to provide more financial support.
Despite the current high iron ore prices, BHP said it believed the addition of low-cost supply in many markets and a maturity in China's infrastructure-led growth would dampen pricing for iron ore and metallurgical coal.
However, copper supply growth in the very near term was expected to result in a more balanced market.
BHP lifted its interim dividend by 3.6 per cent to 57 US cents.