New Zealand Refining ltd has announced a half-year profit of $31.2 million in the six months to the end of June, up 7.5% on the same period the year before.
Revenue rose almost 17% to $158 million.
The company, which runs the country's only oil refinery, attributes the boost to improved margins, but warns that the weak US dollar is an issue since the majority of the income is in US dollars.
Chief executive Ken Rivers says, despite difficult market conditions, refiners' margins have strengthened and the company has paid back more than $32 million in debt.