Transpower says statutory net profit was $71.8 million in the three months to the end of September, slightly lower than the same period last year.
The state-owned national electricity grid operator says underlying profit fell to nearly $51 million from just over $66 million in the year-earlier September quarter.
It says transmission revenue rose 9%, due to the commissioning of new grid assets, while operating expenses rose 7%.
Depreciation, amortisation and asset write-offs rose by 20%, reflecting the commissioning of new assets.
Transpower has paid a total dividend of $294.7 million to the government for the 2013 financial year.
It says its financial performance in the year to date is marginally ahead of plan.