The New Zealand Refining Company recorded a $65.2 million profit for the six months to the end of June.
But a union representing refinery workers says the firm should be sharing some of its profits with its staff, rather than offering them a "miserly" 0.5 per cent pay rise.
The company, which operates the Marsden Pt Oil Refinery, said it had made a Net Profit after tax (NPAT) of $65.2 million for the period ended June 30.
Chief executive Sjoerd Post described the result as a remarkable improvement on the $6.9 million loss reported at the same time last year and vindication of the company's clear strategic formula.
"During the first six months the team capitalised brilliantly on the consistently high margins and improved NZD/USD exchange rate by processing, at times, record volumes at close to, or above margin cap levels.