Centrica has reported a 15% rise in adjusted operating profits to £1.45bn for the period ended 30 June 2012.
Operating profits at the company's residential energy division, British Gas, rose to £345m, up 23% from 2011.
The results also include a 14% rise in residential services to £125m, while total downstream profits in the UK rose by nine percent, to £563m.
Sam Laidlaw, Centrica chief executive, said his company has done well in the first half of 2012 despite challenging market conditions.
"We continue to focus on high standards of service, while ensuring that we run the business as efficiently as possible for the benefit of our customers," said Laidlaw.
"We have made significant investments to secure energy supplies for the UK - and will continue to invest across the Group, where we see value. As a result, we have a stronger business that is delivering benefits for all our stakeholders."
The company said it is on track to achieve a £500m cost reduction programme to maintain competitiveness.
Centrica invested £1.5bn in the first six months of 2012 and said it will bring 140 million barrels of reserves into production this year.