South Korea's H-Line Shipping has ordered two more LNG-fuelled bulkers at Hyundai Samho Heavy Industries.
The yard said it had won the contract for delivery in 2022.
The 180,000-dwt ships will run between South Korea and Australia.
The value of the deal was not given by the shipbuilder.
Last October, the owner ordered the first two in the series for delivery in 2020.
This contract was worth KRW 140bn ($119m) combined.
H-Line has six other bulkers on order: another one at Samho and five at New Times in China.