Ophir Energy fell into the red in the first half after bills mounted up, including the cost of listing on the Main Market of the London Stock Exchange.
In the six months to the end of June the group recorded a loss of $24.4m, compared with a $6.1m profit the year before.
Revenues were £777,000, substantially down from the $14m it posted in the first half of 2011.
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The firm said the loss was a direct result of it listing in July 2011 and the associated regulatory and corporate costs.
Increases in staff in the management team, technical areas and across its London office also impacted, it said.
On top of this there were infrastructure costs resulting from the growth of the company's London office.
However, Ophir's Chairman, Nicholas Smith was upbeat, saying the firm had maintained its successful exploration track record and delivered its largest discovery to date in the first half.
He added that an issue of 30.5m shares, which raised $242m in April, gave Ophir the necessary funding to further explore the resource potential in Tanzania and to progress the rest of the firm's portfolio.
